FORENSIC CHEMISTRY LAB

J.I. Khan et al., Basic Principles of Forensic Chemistry, DOI 10.1007/978-1-59745-437-7, 283 © Springer Science+Business Media, LLC 2012 Preface The goal of this laboratory manual is to provide the student with an enjoyable experience that is both informative and challenging. It is our hope that the thrill of “seeing” theoretical principles “come to life” in the laboratory will enhance your overall understanding, as well as stimulate and develop critical thinking skills. Although there has always been considerable debate over the most effective methods of instruction; many agree that lecture topics supported by practical exercises are a proven model to create a successful learning environment. We embrace the spirit of this model in the Forensic Chemistry Laboratory Manual . Our approach is to correlate laboratory exercises to the theoretical and investigative principles of forensic chemistry. This will provide the student with valuable hands-on experience while adding clarity and continuity to lecture topics. This laboratory manual was written within the framework of each of the following areas. Level and Audience The Forensic Chemistry Laboratory Manual covers the laboratory component of a one semester class in forensic chemistry. It is not designed to be a stand-alone laboratory manual. It was specifi cally written to complement Basic Principles in Forensic Chemistry , the required text for a one semester class offered as part of our forensic certifi cate program. The course requires no prerequisite and is designed for students with little, if any, background in chemistry or forensics. The laboratory exercises are designed to provide practical experience in forensic investigative techniques. Emphasis is on the development of proper technique, handling of evidence, and interpretation of data and results. Although there is brief exposure to more sophisticated chemical principles, it is not the main focus of the manual. It is possible to perform complex procedures and reliably interpret results without an in-depth understanding of the complex reaction mechanisms involved. Forensic Investigation Investigative techniques are developed using evidence and test results from actual case studies. Students learn to exercise due diligence in the formulation of hypotheses, preparation of courtroom testimony, and presentation of results. “Moot” courts are used to develop proper courtroom demeanor, i.e., giving testimony, presenting evidence, jury interaction, etc. In addition, students are exposed to proper format and writing techniques typically used in the submission of case reports. Stockroom Preparation It was important to develop experiments that require chemicals and laboratory equipment that is both inexpensive and readily available. Safety Forensic chemical analysis is often performed by highly trained scientists in a controlled environment. Consequently, a few procedures used in forensic investigation have been intentionally omitted. These omissions may be based on reagent cost or availability, lack of analytical instrumentation or specialized glassware, or safety concerns when working with potentially dangerous chemicals. In these few cases, data and/or test results are provided for interpretation and presentation purposes only. Strict adherence to all safety procedures is highly stressed. Laboratory Manual 284 Laboratory Manual To The Student We wish you success as you begin your journey into forensic chemistry. This manual was specifi cally designed to illustrate principles and techniques commonly used in forensic investigation. All too often, students fail to realize (or appreciate) the importance of practical laboratory experience and its relationship to theoretical principles. Lost in the topics presented in lecture are the long hours scientists spend in the laboratory developing and proving these theories. As you perform the experiments in this manual, you will learn proper experimental technique and develop an appreciation of the correlation that exists between theory and practice. We hope that your laboratory experience is enjoyable and informative. Strict adherence to safety procedures will create a relatively safe and hazard free laboratory environment. It is the responsibility of each student to contribute to this safe environment by following all safety rules and regulations. The following list of safety procedures should be followed at all times. Your laboratory may have specifi c safety rules and practices, in addition to those below, that will be thoroughly explained by your laboratory instructor. Wear approved safety glasses or goggles at all times If you have contact lenses, nonvented goggles are required. Prepare for lab Read the experiment carefully and be aware of potential hazards before coming to lab. Dress for lab No loose fi tting cloths, no shorts, no open-toed shoes, no tank tops. Tie long hair back to prevent contact with an open-fl ame. Lab coats or aprons are highly recommended and may be available in lab. No food or drinks are allowed in the laboratory Chemicals may adhere to food or liquids and may cause illness. If you take a break to eat, wash your hands thoroughly. Know the location and proper use of all safety equipment Survey the lab and locate all exits, safety showers, fi re extinguishers, fi re blankets, eye wash facilities, emergency gas shutoff valves, emergency phones, etc. No unauthorized experiments Closely follow the instructions given in this manual. Do not deviate from the procedures or techniques explained. Practice proper laboratory behavior at all time Do not take unnecessary risks. Playing or “horsing around” in lab will not be tolerated and will result in your expulsion. Handle all chemicals properly Never taste chemicals or inhale chemical vapors. Avoid direct contact of chemicals with skin. Never pour excess chemicals back into the original container. Your instructor will advise you in the proper disposal of waste material. Keep your work area neat and organized Do not clutter your work area with excessive chemicals, glassware, and books. Smoking is not permitted in the laboratory Report all accidents to your instructor Report all accidents, no matter how small, to your laboratory instructor. This information may be used to further develop and/ or refi ne existing safety procedures. Laboratory Manual 285 If you have questions ASK YOUR INSTRUCTOR Your instructor is a trained professional who is very familiar with the procedures performed in each experiment. If you have questions or require clarifi cation, do not hesitate to ask. The above represents a list of minimum safety precautions that should be followed to create a safe laboratory environment. Following these procedures will not guarantee a safe, accident-free environment, nor are they intended to represent a complete list of all safety rules and regulations. The possibility of accident and/or injury is always present in the lab; however, strict adherence to proper safety procedures at all times will minimize the risk for such occurrences. Laboratory Manual Table of contents Experiment Topic 1 Introduction and Safety 2 Forensic/Scientifi c Investigation and Atomic Structure 3 Properties of Elements 4 Mixtures and Compounds 5 Chemical Formulas and Nomenclature 6 Solubility 7 Molecular Geometry 8 Organic Chemistry and Functional Groups 9 Microcrystallography 10 Chemical Extraction 11 Chromatography 12 Interpretation of GCMS Spectra 13 IR Spectroscopy 14 Examination of Marijuana (moot) 15 Examination of Controlled Substances: Primary and Secondary Amines (moot) 16 Examination of Controlled Substances: Tertiary Amines and Opiates (moot) 17 Examination of Controlled Substances: Tryptamines (moot) 18 Examination of Anabolic Steroids (moot) 19 Examination of Miscellaneous Controlled Substances (moot) 20 Clandestine Manufacturing of Methamphetamine (moot) 286 Laboratory Manual Experiment # 2 Name _____________________________________ Forensic/Scientifi c Investigation and Atomic Structure Reference: Chapters 1 and 2 Objectives: Students will gain practical experience using the scientifi c method to develop conclusions. Students will become familiar with atomic structure and writing electron confi gurations for ground state neutral atoms and ions. Introduction: Scientifi c discoveries are usually the result of a systematic approach to a good idea or an unexplained observation. Although many variations of this “systematic” approach exist, it often involves a stepwise process called the scientifi c method . The scientifi c method is a procedure used to develop technical theories and generally includes four phases; observation, hypothesis, experimentation, and theory . It begins with the observation of some type of unexplained phenomenon. A possible cause of the observation is proposed during the hypothesis phase. Experiments are then specifi cally designed in order to prove the hypothesis. If experimental results do not support the hypothesis another possibility is considered and tested. If experimental results confi rm the hypothesis, and are consistently reproducible, a formal explanation is developed and subsequently offered as a theory. The theory is then presented to the scientifi c community where it may be accepted or rejected. If accepted, it may become a principle or a law . Part: A: Forensic/ Scientifi c Investigation Observation: Different types of cell phone ring tones. Hypothesis: No cell phones are currently set to identical ring tones Experiment: Each student that has a cell phone will play their ring tone. Record the results. Theory: Part B: Atomic Structure Complete the following table Symbol # Protons # Neutrons # Electrons Atomic Mass H 1 19 19 K + 39 B 6 11 5 2 Cl 17 Cl - 17 Laboratory Manual 287 Part C: Electron Confi guration Write the electron confi guration for each of the following. Mg (atomic mass = 24) Mg 2+ (atomic mass = 24) C (atomic mass = 12) N 3- (atomic mass = 14) Ca (atomic mass = 40) Cl - (atomic mass = 35.45) H (atomic mass = 1) 288 Laboratory Manual Experiment # 3 Name ____________________________ Properties of Elements Reference: Chapter 3 Objectives: Students will distinguish the difference between a chemical property and a physical property. Students will gain practical experience in the use of properties to identify elements and compounds. Materials: 1M hydroiodic acid (HI), 1M hydrochloric acid (HCl), 0.3M hypophosphorous acid (H 3 PO 2 ), 0.5M sulfuric acid (H 2 SO 4 ), 1M acetic acid (HC 2 H 3 O 2 ), 3% silver nitrate solution (AgNO 3 ), 1% iodine solution in water, chloroform (CHCl 3 ), starch (sugar), sodium nitrite (NaNO 2 ), test tubes, matches, and wax pencils. Introduction: There are fundamental properties associated with all forms of matter. These distinguishing characteristics may be physical or chemical in nature, and are commonly used to identify and classify a particular substance. A physical property is anything that can be measured or observed without changing chemical composition. The melting point and boiling point of water are examples of physical properties because these temperatures can be measured without changing the chemical composition of water. A physical change is a change in the state of matter, but not its chemical composition. There are three accepted states of matter; solid, liquid, and gas (although some would argue plasma is also a state). Other physical properties commonly used in the forensic identifi cation of elements and compounds are: color, odor, density, solubility, conductivity, and sublimation. Chemical properties are a measure of the ability of a substance to produce new substances, or simply, a measure of the reactivity of a substance. Chemical changes are transformations that produce products chemically and physically different from the starting material. A solution containing silver nitrate will produce a white precipitate (solid) in the presence of chloride ions and a yellow precipitate in the presence of iodide ions. These observations illustrate the chemical changes that result from the reactivity (chemical properties) of silver nitrate. Physical and chemical properties are commonly used to identify elements and compounds in the fi eld of forensic science. Consequently, these properties may be used to support or reject specifi c parts of an investigation. Part A: Clean fi ve test tubes and label each with the name of an acid shown below. Place 10 drops (approx. ½ ml) of the corresponding acid into each of the labeled test tubes. Add 1–2 drops of 3% silver nitrate solution (AgNO 3 ) to each test tube and observe the results. If a precipitate (solid) forms, record the color below next to the corresponding acid. If no precipitate is observed, write “none.” Acid Color of Precipitate Hydroiodic acid Hydrochloric acid Hypophosphorous acid Sulfuric acid Acetic acid Conclusion: Laboratory Manual 289 Part B: Strike a matchstick on the following surfaces and record your observations. Nature of Surface Ignite (yes/no) Wood Cement Metal Plastic Paper Course sandpaper (matchbox) Conclusion: Part C: Clean three test tubes and label each with a reagent shown below. Place ten drops (approx. ½ ml) of 1% iodine solution in each test tube and add the corresponding reagent. Record your observations. Reagent Add Observation Starch Approx. “½ pea size” of starch Chloroform 1 ml chloroform Acetic acid 1 ml acetic acid Conclusion: 290 Laboratory Manual Experiment # 4 Name_______________________________ Mixtures and Compounds Reference: Chapters 1, 2, and 3 Objective: Students will observe common properties of mixtures and compounds. Materials: methanol, DI water, sugar, salt, analytical balance, watch glass, and oven. Introduction: Elements and compounds may exist as pure substances or as mixtures. Pure substances contain only one component and have the same composition throughout, i.e., pure gold, pure sugar, pure water, etc. Mixtures contain two or more pure substances and may be homogeneous or heterogeneous. Homogeneous mixtures have the same composition and properties throughout. However, they are not pure substances because they contain more than one component. Heterogeneous mixtures have distinctly different properties within the mixture; water and sand would be an example. In any binary solution (a solution that contains only two components), the solvent is the component present in greatest amount and the solute is the component present in least amount. The following mixtures will be provided. Classify each mixture by circling homogeneous or heterogeneous. Solution #1 Sugar in water (sat.) homogeneous or heterogeneous Solution #2 Salt in water (sat.) homogeneous or heterogeneous Solution #3 Sugar in methanol (sat.) homogeneous or heterogeneous Solution #4 Salt in methanol (sat.) homogeneous or heterogeneous Part A: Clean and dry four watch glasses and label each 1, 2, 3, or 4. Weigh each empty watch glass on an analytical balance and record the mass in the table below under “watch glass.” Be sure to weigh the watch glasses after they are labeled! Place 1.0 ml of the corresponding solutions above on each of the labeled watch glasses, i.e., place 1.0 ml of solution #1 on watch glass labeled 1, etc. Using the same analytical balance that was used to weigh the empty watch glasses, carefully weigh the watch glasses containing each solution. Determine the mixture mass for each solution by subtracting the mass of the empty watch glass from the mass of the watch glass containing solution. Record the mass of each mixture in the table below under “mixture mass.” Save the watch glasses containing each solution for Part B. Clean and dry two small test tubes and place one test tube into a small beaker. Place the test tube/beaker on the analytical balance and tare the balance (zero the balance with the test tube/beaker on the pan). Place 1.0 ml of water into the test tube and record the mass in the table below under Solvent Mass for water. Repeat the procedure using the other test tube and 1.0 ml of methanol. Record the mass below under Solvent Mass for methanol (water is the solvent in solutions 1 and 2, methanol is the solvent in solutions 3 and 4). Subtract the solvent mass from the mixture mass and record the difference in the table below under “solute mass.” Watch Glass Mixture Mass Solvent Mass Solute mass #1- Water- #2- Water- #3- Methanol- #4- Methanol- What is the mass of sugar in mixture #1? What is the mass of salt in mixture #2? What is the mass of sugar in mixture #3? What is the mass of salt in mixture #4? Laboratory Manual 291 Did the mixture mass exceed the solvent mass in any solution? If so, explain. Did the solvent mass exceed the mixture mass in any solution? If so, explain. Did the solvent mass equal the mixture mass in any solution? If so, explain. Explain your observed results using your knowledge of homogeneous and heterogeneous mixtures. Part B: Carefully place the watch glasses containing each solution in the oven and evaporate the solvent to dryness. When evaporation is complete, weigh each watch glass and record the mass in the table below under “watch glass/residue.” Determine the mass of the residue by subtracting the mass of the empty watch glass (measured in Part A) from the mass of the watch glass/ residue. The residue is the actual mass of solute contained in each solution. Record the residue mass in the table below under “solute mass (actual).” Watch Glass/Residue Solute Mass (actual) What is the actual mass of sugar in mixture #1? What is the actual mass of salt in mixture #2? What is the actual mass of sugar in mixture #3? What is the actual mass of salt in mixture #4? Conclusion: (Hint: Defi nition of solution; did any of the 1.0 ml solutions actually contain 1.0 ml of solvent?) 292 Laboratory Manual Chemical Formulas and Nomenclature Reference: Chapters 2 and 3 Objective: Students will gain experience writing chemical formulas for ionic compounds. Students will learn formal procedures used to name ionic and covalent compounds. Introduction: Substances are either elements or compounds. A compound is a substance that consists of two or more elements bonded together in a specifi c way. The forces that hold atoms together in a compound are called chemical bonds. An ionic bond involves the transfer of electrons from a metal to a nonmetal . A covalent bond consists of a pair of electrons shared between two nonmetals . Ions and the Octet Rule Atoms are electrically neutral because they have an equal number of electrons and protons. An atom can be converted into a charged particle called an ion by losing or gaining one or more electrons. The loss of electron(s) from a neutral atom produces a positively charged ion called a cation (pronounced cat-ion). The gain of electron(s) by a neutral atom produces a negatively charged ion called an anion (pronounced an-ion). Generally, the charge on an ion can be predicted from the position of the element on the periodic table. The metals (on the left-hand side of the table) lose electrons to form cations. The Group IA elements lose ONE electron to achieve an octet and take a charge of 1 positive. This is correctly written using a superscript “+” attached to the upper right side of the elemental symbol, i.e., Na + . Notice that the number “1” is not written when the cation carries a positive one charge. The Group IIA elements lose TWO electrons and take a charge of 2 positives. This is correctly written using a superscript “2+” attached to the upper right side of the elemental symbol, i.e., Mg 2+ . When cations carry a charge greater than one, the number is written fi rst, followed by the sign. The Group IIIA elements lose THREE electrons and take a charge of 3 positives which is written as a superscript “3+”, i.e., Al 3+ . The nonmetals (on the right-hand side of the table) gain electrons to form anions. The Group VIIA elements gain ONE electron to achieve an octet and take a charge of 1 negative. This is written using a superscript “-“ attached to the elemental symbol, i.e., Cl - . Once again, the “1” is not written. The Group VIA elements gain TWO electrons and take a charge of 2 negatives which is written as a superscript “2-“, i.e., O 2- . The Group VA elements gain THREE electrons and take a charge of 3 negatives which is written as superscript “3-“, i.e., N 3- . Some transition metals and metals in Group IVA have variable charges (more than one positive ion is possible). See table below. Some common ions and their location on the periodic table. IA IIA IIIA IVA VA VIA VIIA H + Li + Be 2+ N 3- O 2- F - Na + Mg 2+ Al 3+ P 3- S 2- Cl - K + Ca 2+ Fe 2+ Fe 3+ Co 2+ Co 3+ Ni 2+ Cu + Cu 2+ Zn 2+ Br - Rb + Sr 2+ Ag + Sn 2+ Sn 4+ I - Cs + Ba 2+ Hg 2 2+ Hg 2+ Pb 2+ Pb 4+ Experiment # 5 Name __________________________________ Laboratory Manual 293 Writing Formulas for Ionic Compounds Ionic compounds are electrically neutral . Therefore, when writing formulas, the cations (positive) and anions (negative) must combine to produce a net charge of zero. In the formula, the cation (metal) is always written fi rst, followed by the anion (nonmetal). The number and types of each element must be clearly shown in the formula; the type of element is indicated using the elemental symbol, and the number of each element is indicated using a subscript attached at the lower right side of the symbol. The number “1” is not written in cases requiring only a single element. Formulas for ionic compounds are called formula units . The correct ratio required to produce a net charge of zero when Na + ions combine with Cl - ions is one to one because one Na + cancels one Cl - . Therefore, the formula is NaCl. Notice this is not written Na 1 Cl 1 . The correct ratio when Na + ions combine with O 2- ions is two to one because two Na + are required to cancel one O 2- . The 2 atoms of Na are indicated in the formula using a subscript “2” directly attached to Na. The formula is Na 2 O. The correct combining ratio when Na + ions and P 3- ions combine is: Na 3 P (three to one). Practice Examples: Write the formula for the ionic compound that is formed when each of the following pairs of ions interact: a) K + and S 2- b) Mg 2+ and O 2- c) Ca 2+ and I - d) Li + and N 3- e) Al 3+ and S 2- Solution (a) The cation has a charge of 1+ because K is a member of Group IA. The anion has a charge of 2- because S is member of Group VIA. Thus, two positive ions (2+) are required for each negative ion (2-) to produce an electrically neutra l formula unit. The formula is K2 S . (b) The cation has a charge of 2+ and anion has a charge of 2-. The ratio is 1:1. The formula is MgO . (c) The cation has a charge of 2+ and anion has a charge of 1-. Two negative ions are required for each positive ion. The formula is CaI2 . (d) The cation has a charge of 1+ and anion has a charge of 3-. Three positive ions are required for each negative ion. The formula is Li3 N . (e) The cation has a charge of 3+ and anion has a charge of 2-. Two positive ions are required for three negative ions. Here, the lowest common factor of 3+ and 2- is 6 (without sign). The formula is Al2 S3 . Naming Ions The names of cations and anions are determined by a system developed by the International Union of Pure and Applied Chemistry (IUPAC). Metals That Form Only One Type of Positive Ion Elements in Groups IA, IIA, IIIA, and some transition elements form only one type of cation. For these ions, the name of the cation is the elemental name of the metal followed by the word “ion.” Cations can now be differentiated from their corresponding neutral forms using specifi c names. For example, K is potassium (neutral form) and K + is potassium ion (cationic form). Na + sodium ion K + potassium ion Mg 2+ magnesium ion Al 3+ aluminum ion Ag + silver ion Zn 2+ zinc ion Metals That Form Two Different Positive ions Metals in Group IVA, and most transition metals, form more than one type of cation and the charge must be included in the name. For these ions, the name of the cation is the elemental name of the metal followed by a Roman numeral in parentheses, with no space after the name. The Roman numeral indicates the positive charge on the ion. Technically, the names do not end with the word “ion,” although some still prefer to include it. 294 Laboratory Manual Sn 2+ tin(II) Sn 4+ tin(IV) Pb 2+ lead(II) Pb 4+ lead(IV) Cu + copper(I) Cu 2+ copper(II) Fe 2+ iron(II) Fe 3+ iron(III) Co 2+ cobalt(II) Co 3+ cobalt(III) Hg 2 2+ mercury(I) Hg 2+ mercury(II) Naming Anions Anions are named by replacing the last part of the elemental name with the suffi x –ide , and adding the word “ion”. Anions can now be differentiated from their corresponding neutral forms using specifi c names. For example, S is sulfur (neutral form) and S 2- is sulf ide (anionic form). F - fl uoride ion Cl - chloride ion Br - bromide ion I - iodide ion O 2- oxide ion S 2- sulfi de ion N 3- nitride ion P 3- phosphide ion Polyatomic Ions A polyatomic ion is an ion that contains two or more elements. It is recommended that you memorize the names and formulas of the following polyatomic ions: NH 4 + ammonium SO 3 2- sulfi te CN - cyanide SO 4 2- sulfate OH - hydroxide HSO 3 - hydrogen sulfi te C 2 H 3 O 2 - acetate HSO 4 - hydrogen sulfate CrO 4 2- chromate PO 3 3- phosphite Cr 2 O 7 2- dichromate PO 4 3- phosphate MnO 4 - permanganate HPO 4 2- hydrogen phosphate NO 2 - nitrite ClO - hypochlorite NO 3 - nitrate ClO 2 - chlorite CO 3 2- carbonate ClO 3 - chlorate HCO 3 - hydrogen carbonate ClO 4 - perchlorate The common name for HCO 3 - , HSO 3 - , and HSO 4 - are bicarbonate, bisulfi te, and bisulfate respectively. Naming Ionic Compounds Binary ionic compounds containing metals that form only one type of positive ion These compounds contain only two types of elements; a metal ion and a nonmetal ion. Note: binary refers to element types, not total number of atoms. For example; MgBr 2 contains 3 total atoms, 1 Mg and 2 Br’s, but it contains only two types, Mg and Br. Also, recall all elemental symbols begin with capital letters, if you have a binary compound, your formula contains only two capital letters. The metal is always named fi rst using the elemental name of the metal. The nonmetal is named second using the anionic name of the nonmetal (elemental name modifi ed with the suffi x –ide ). Practice Examples: Name the following binary ionic compounds: NaCl MgBr 2 AlP K 2 S SrF 2 ZnI 2 Solution NaCl sodium chloride K 2 S potassium sulfi de MgBr 2 magnesium bromide SrF 2 strontium fl uoride AlP aluminum phosphide ZnI 2 zinc iodide Binary ionic compounds containing metals that form two different positive ions These compounds are essentially named using the same procedure developed for metals forming only one type of cation. The distinction is that the charge on the cation must be written as a Roman numeral in parentheses immediately after (with no space) the metal name. Laboratory Manual 295 Practice Examples: Name the following binary ionic compounds: FeBr 3 CoF 2 SnO PbI 4 HgS Cu 3 P Solution FeBr 3 iron(III) bromide PbI 4 lead(IV) iodide CoF 2 cobalt(II) fl ouride HgS mercury(II) sulfi de SnO tin(II) oxide Cu 3 P copper(I) phosphide Ionic compounds containing polyatomic ions Identifying compounds containing polyatomic ions is somewhat simplifi ed by the fact that all elemental symbols begin with capital letters. If you identify more than two capital letters in the formula, your compound contains a polyatomic ion that you must immediately recognize (the value of memorizing!). Naming these compounds is simply based on your familiarity with the polyatomic ions. The cation is named fi rst using its elemental name, followed by the name of the polyatomic ion. Practice Examples: Name the following polyatomic ionic compounds: Ca(NO 3 ) 2 ZnSO 4 NH 4 CN Li 3 PO 4 Na 2 CO 3 Mg(HCO 3 ) 2 Solution Ca(NO 3 ) 2 calcium nitrate ZnSO 4 zinc sulfate NH 4 CN ammonium cyanide Li 3 PO 4 lithium phosphate Na 2 CO 3 sodium carbonate Mg(HCO 3 ) 2 magnesium hydrogen carbonate Compounds containing only nonmetals (molecular compounds) This type of compound contains covalent bonds, so the concept of cations and anions is somewhat obscure and does not necessarily apply. Regardless, they are essentially named using the previously developed procedure for naming binary compounds containing a metal. The fi rst element is named using its elemental name and the second is named using its anionic name. The difference is the use of Greek prefi xes attached to each name, which indicate the number of each element present in the formula. There is one important exception; the prefi x “mono” is never attached to the name of the fi rst element in the formula. Let us look at SF 6 as an example. You should immediately notice that S and F are nonmetals because both are located in the nonmetal section of the periodic table (right side). This observation should immediately trigger “prefi xes” in your mind. SF 6 is sulfur hexafl uoride because the formula indicates one sulfur (note the absence of the subscript “1” attached to S) and 6 fl uorides (subscript 6 attached to F). This is not monosulfur hexafl uoride because “mono” is never used with the fi rst element. It is possible, however, to attach all other prefi xes to the name of the fi rst element, i.e., N 2 O 5 is dinitrogen pentoxide. The Greek prefi xes are listed below, note that all end in a vowel. When the prefi x ends with an “a” or “o”, and the elemental name begins with an “a” or “o”, the vowel of the prefi x is usually dropped to simplify pronunciation. Notice in our N 2 O 5 example above, the name of the anion is pentoxide, not pentaoxide. Greek prefi xes 1 (mono-) 2 (di-) 3 (tri-) 4 (tetra-) 5 (penta-) 6 (hexa-) 7 (hepta-) 8 (octa-) 9 (nona-) 10 (deca-) Practice Examples: Name the following binary molecular compounds: N 2 O 5 CO 2 P 4 S 3 XeF 6 ICl NH 3 I 4 O 9 CO H 2 O H 2 O 2296 Laboratory Manual Solution N 2 O 5 dinitrogen pentoxide NH 3 nitrogen trihydride (ammonia) CO 2 carbon dioxide I 4 O 9 tetraiodine nonoxide P 4 S 3 tetraphosphorous trisulfi de CO carbon monoxide XeF 6 xenon hexafl uoride H 2 O dihydrogen monoxide (water) ICl iodine monochloride H 2 O 2 dihydrogen dioxide Exercises Inspect the periodic table and list ALL elements with a ONE letter abbreviation. Symbol Name Period number Group number metal, nonmetal, or metalloid Formulas of Ionic Compounds Complete the following table with the formula of the compound. Br - O 2- NO 3 - PO 4 3- Na + Mg 2+ Al 3+ Pb 4+ NH 4 + Fe 2+ Fe 3+ Ionic Compounds Write the correct name for each of the following ionic compounds. Formula Name Pb(HCO 3 ) 4 Al 2 S 3 LiHSO 4 Zn 3 (PO 4 ) 2 CoF 3 Ca(CN) 2 SnO 2 Na 2 CrO 4 K 2 CO 3 Cu 3 P Sr(OH) 2 (NH 4 ) 2 HPO 4 Hg 2 Cl 2Laboratory Manual 297 Formula Name BaSO 4 Sn(NO 3 ) 2 AgClO 3 Cu(HSO 3 ) 2 Molecular Compounds Name each of the following compounds. Formula Name BBr 3 Br 3 O 8 CI 4 C 3 O 2 Cl 2 O 7 IF 5 I 2 O 5 NCl 3 N 2 O 5 OF 2 P 4 S 3 P 4 S 9 P 4 O 10 SF 6 S 2 Cl 2 SiS 2 SiBr 4 XeF 2 XeO 4 XeF 6298 Laboratory Manual Experiment # 6 Name ________________________________ Solubility Reference: Chapter 3 Objective: Students will test the solvent properties of various liquids to observe and understand the chemical nature of solubility and miscibility. Materials: acetone, chloroform, ammonia, methanol, water, test tubes, and pipettes. Introduction: Water is a common solvent in many solutions and substances like salt and sugar readily dissolve in water. Any substance that dissolves appreciatively in a specifi ed solvent is said to be soluble in that solvent. Technically, the term solubility refers to a quantitative maximum amount of substance that can dissolve in a given volume of solvent at a specifi c temperature. The ability of a substance to dissolve in a particular solvent depends on the identity of both the solvent and the substance; the general rule is “likes dissolve likes.” Water is a polar covalent molecule and, as a solvent, can dissolve similar molecules (polar covalent). The polarity of water is responsible for its remarkable solvent properties and explains why ionic compounds (i.e., NaCl) and polar covalent compounds (i.e., sucrose, ammonia) are soluble, whereas nonpolar molecules (i.e., organic, gasoline, oils) are not. Terms such as soluble, slightly soluble, insoluble, and solubility are used to describe the ability of a substance to dissolve in a solvent. Intuitively, we associate the term “dissolving” with solids and liquids; however, a liquid may also be soluble in another liquid. For example, when 25.0 ml of ether is added to 25.0 ml of water, the resulting total volume is not 50.0 ml, in fact, it is slightly less (approx. 48.5 ml). This is the result of solubility; ether and water are slightly soluble in one another and consequently, the volumes are not additive. The solubility of one liquid in another is diffi cult to determine and is usually not readily observed upon mixing. For this reason, liquids are often characterized using their ability to mix with other liquids rather than their solubility in other liquids. The degree of mixing between two liquids is described using the terms miscible and immiscible . Two liquids are miscible (soluble) if a uniform solution results after mixing (i.e., water and ammonia). Two liquids are immiscible (insoluble) if two distinct layers form after mixing (i.e., oil and water). Water is miscible in polar liquids and immiscible in nonpolar (organic) liquids. Part A: Add 1.0 ml of each of the following reagents to four separate, clean, and dried test tubes: chloroform, ammonia, methanol, water. Add 1.0 ml of acetone to each test tube and mix. Observe the results and characterize the liquids as miscible ( M ) or immiscible ( I ). Record your results in the table below under the corresponding reagents. Clean and dry three test tubes and add 1.0 ml of each of the following reagents to separate test tubes: ammonia, methanol, water. Add 1.0 ml of chloroform to each test tube and mix. Record your results in the table below under the corresponding reagents. Clean and dry two test tubes and add 1.0 ml of each of the following reagents to separate test tubes: methanol, water. Add 1.0 ml of ammonia to each test tube and mix. Record your results in the table below under the corresponding reagents. Clean and dry one test tube and add 1.0 ml of methanol and 1.0 ml of water to the test tube and mix. Record your results in the table below under the corresponding reagents. Reagents Chloroform Ammonia Methanol Water Acetone Chloroform -------------- Ammonia -------------- ------------ Methanol -------------- ------------ ------------ Laboratory Manual 299 Identify the organic liquids: Identify the inorganic liquids: What liquids are polar? What liquids appear to be non-polar? List the liquid-pairs that are miscible: List the liquid-pairs that are immiscible: Are immiscible liquids soluble in one another? Briefl y explain. Are miscible liquids soluble in one another? Briefl y explain. 300 Laboratory Manual Experiment # 7 Name ______________________________ Molecular Geometry Reference: Chapter 3 Objective: To illustrate the geometric structures of simple molecules and to demonstrate the relationship between bonding and molecular geometry. Materials: Molecular model kits. Introduction: In recent years, advancements in research and technology have provided precise information on molecular geometry, i.e., bond distances, angles, and energies. Structural theory has advanced far beyond the simple electron dot representation and now rests securely on the foundations of quantum and wave mechanics. Although problems involving only simple molecules can be solved through rigorous mathematical calculations, approximations such as Valence Bond Theory (VBT) and Molecular Orbital Theory (MOT) are very successful in providing results that agree favorably with experimental measurements. This exercise will utilize Valence Bond Theory to illustrate the geometry of a variety of simple molecules. This will be accomplished through the use of model kits that show the correct angles formed between atoms in the molecule. The fi rst covalent bond formed between any two atoms is always a sigma-bond ( s -bond). This type of bond has electrons distributed symmetrically about the bond axis and is used to defi ne the bond axis. Additional bonds (double or triple) formed between the same two atoms will be pi-bonds ( p -bonds). These bonds are perpendicular to the defi ned s -bond and do not infl uence geometry. It is the s -bonds, and any lone pairs of electrons occupying sigma hybrid orbitals, that determine molecular geometry. Model kits are a necessary and integral part of the study of molecular geometry. They are tools that allow students to transcend the inherent diffi culties that arise from visualizing a three dimensional structure on a two dimensional piece of paper. A complete understanding of the capabilities and limitations of model kits is essential in their successful use as a visual aid. Open your model kits and carefully read the instructions. Inventory the various pieces contained in your kit and pay special attention to the color codes used to designate specifi c atoms. It is important that you take the time now to familiarize yourself with all the components contained in your kit. This will allow you to concentrate on the structure or concept currently under study and prevent wasted time (and confusion) that may result from constantly referring back to the instructions. A table is included at the end of the lab for reference. Methane (CH 4 ) Construct a model of methane using your model kit. Locate a tetrahedral center (a carbon atom) and attach four rods (bonds) in each hole of the atom. Attach 4 balls (hydrogen atoms) of the same color to each rod extending from your structure. Sketch the model using the solid/dashed wedge convention and name the geometry. Write the structural formula. Write the condensed structural formula. What are the H–C–H bond angles?___________________ How many s -bonds are on the central carbon?___________________ Identify the two planes present in this molecule. Do the planes divide the molecule into equal halves?________________ How many atoms, including carbon, are in the same plane?__________________ Laboratory Manual 301 Ammonia (NH 3 ) Construct a model of ammonia using your model kit. Sketch the model, including the lone pair of electrons, and name the geometry. Write the structural formula. Write the condensed structural formula. What is the H–N–H bond angle?__________________ How many s -bonds are on the central nitrogen?__________________ How many lone pairs are on the central nitrogen?__________________ Are any atoms in ammonia in the same plane?__________________ Suggest a reason why the H–N–H bond angles in ammonia differ from the H–C–H bond angles observed in methane. Water (H 2 O) Construct a model of water using your model kit. Sketch the model, including lone pairs of electrons, and name the geometry. Write the structural formula. Write the condensed structural formula. What is the H–O–H bond angle? ____________________ How many s -bonds are on the central oxygen? _________________ How many lone pairs are on the central oxygen? ______________________ How many atoms, including oxygen, are in the same plane? __________________ Why is the H–O–H bond angle slightly smaller than the bond angles observed in ammonia and methane? What conclusions can be made on how lone pairs affect molecular geometry? 302 Laboratory Manual Sulfur Hexafl uoride (SF 6 ) Construct a model of sulfur hexafl uoride using your model kit. Sketch the model and name the geometry. Write the structural formula. Write the condensed structural formula. What are the F–S–F bond angles? ___________________ How many s -bonds are on the central sulfur? ________________ How many lone pairs are on the central sulfur? ____________________ How many atoms, including sulfur, are in the same plane? __________________ Carbon Dioxide (CO 2 ) Construct a model of carbon dioxide using your model kit. Sketch the model and name the geometry. Write the structural formula. Write the condensed structural formula. What is the O–C–O bond angle? __________________ How many s -bonds are on the central carbon? ____________________ How many p -bonds are on the central carbon? _________________ How many lone pairs are on the central carbon? ___________________ How many atoms are in the same plane? ______________________ Laboratory Manual 303 Lone pairs Bonded atoms a Geometry Molecular Shape Examples 0 2 Linear Cl Be Cl OCO 180° 180° 0 3 Trigonal Planar 120° F B F F 0 4 Tetrahedral C H H H H 109.5° 1 3 Trigonal Pyramidal lone pair 107° N H H H 2 2 Angular (bent) lone pairs O H H 104.5° 0 5 Trigonal Bipyramidal 120° 180° 90° P F F F F F 0 6 Octahedral 180° 90° F F F F F S F aTechnically this should read # of s -bonds. A single bond contains 1 s -bond and 0 p -bonds, double bonds contain 1 s - and 1 p -bond, triple bonds contain 1 s - and 2 p -bonds. Therefore, when counting bonded atoms to determine molecular geometry, count single bonds as 1, double bonds as 1, and triple bonds as 1. See CO 2 example above. 304 Laboratory Manual Experiment # 8 Name __________________________________ Organic Chemistry and Functional Groups Reference: Chapter 4 Objective: Students will gain experience in the basic recognition of functional groups present in a variety of organic molecules. Materials: Molecular model kits. Introduction: Organic chemistry is the study of the properties, structure, and function of compounds containing carbon. Although the defi ning element in organic molecules is carbon, it is common practice to defi ne them by the obligate presence of both carbon and hydrogen. This does not mean that organic molecules contain only carbon and hydrogen; elements such as nitrogen, oxygen, sulfur, phosphorous, and chlorine may also be present. The study of organic chemistry does not involve the individual study of the vast number of organic compounds. Instead, organic compounds are divided into broad classes based on the presence of a functional group . Functional groups are atoms, groups of atoms, or common structural features used to classify organic molecules. In general, functional groups will react in a unique, predictive manner and this chemical behavior is similar in all compounds containing a specifi c group. It is possible, and quite common indeed, to have more than one functional group on a single molecule. In these cases, the molecule will exhibit chemical and physical properties of all groups present. The study of functional groups is the most effective and effi cient approach to the study of organic chemistry. A wide range of functional groups can be found on various types of controlled substances. Part A: Use model kits to construct the following molecules using their chemical formulas. Rotate each structure in space and observe the geometry from different perspectives. Compare the structures of different molecules and determine some factors that infl uence geometry, i.e., number and types of bonds present, bond orientation on central atom, number of atoms in the molecule, etc. Draw the structures of each molecule. Alkanes: Name Formula Structure Methane CH 4 Ethane C 2 H 6 Propane C 3 H 8 Butane C 4 H 10 Alkenes: Name Formula Structure Ethene C 2 H 4 Propene C 3 H 6 1-Butene C 4 H 8 2-Butene C 4 H 8Laboratory Manual 305 1-Butene and 2-Butene are positional isomers because they have the same molecular formula and differ only in the location of the double bond. Alkynes: Name Formula Structure Acetylene C 2 H 2 (Ethyne) Propyne C 3 H 4 1-Butyne C 4 H 6 2-Butyne C 4 H 6 Note: acetylene does not contain a double bond despite its “ene” ending. Alcohols: Name Formula Structure Ethanol C 2 H 5 OH Propanol C 3 H 7 OH Isopropanol C 3 H 7 OH (Isopropyl alcohol) 1-Butanol C 4 H 9 OH 2-Butanol C 4 H 9 OH Aldehydes: Name Formula Structure Formaldehyde HCHO (Methanal) Acetaldehyde CH 3 CHO (Ethanal) Propanal CH 3 CH 2 CHO Butanal CH 3 CH 2 CH 2 CHO Note: The location of the aldehyde functional group will always be carbon # 1. Carboxylic Acids: Name Formula Structure Formic Acid HCOOH Acetic Acid CH 3 COOH (Ethanoic Acid) Propanoic Acid CH 3 CH 2 COOH Butanoic Acid CH 3 CH 2 CH 2 COOH Others: Name Formula Structure Chloroform CHCl 3 Benzene C 6 H 6 Cyclohexane C 6 H 12 Draw structures for the following: 1-bromo-2,2-dichloropentane 2-methyl-3-heptene 306 Laboratory Manual 1-chloro-1-pentanol 3-isopropyloctane 3-methylbutanal 4-chloropentanoic acid Name the following: Cl Cl Br Br OH O OH H OLaboratory Manual 307 Part B: Circle and name all functional groups present in each of the following compounds. A table of functional groups is provided on the last page of the lab. NH2 CH3 O Cathinone N PCP NH CH3 CH3 O Methcathinone N N O CH3 N H H LSD H3C O O O O CH3 O N CH3 H Heroine HO HO O N CH3 H Morphine308 Laboratory Manual Part C: The structure below is tryptamine when all R-groups are hydrogen (H). Substitute the groups indicated in the table below for each corresponding “R” and name the resulting compounds (reference Chap. 15). N N R2 R1 R4 R3 1 2 3 4 5 R 1 R 2 R 3 R 4 Name H H H H Tryptamine CH 3 CH 3 H H CH 3 CH 3 H OH CH 3 CH 3 OH H CH 3 CH 3 PO 4 3- H C 2 H 5 C 2 H 5 H H CH 3 CH 3 H OCH 3 Part D: Use your model kit to construct pseudoephedrine as shown below. Replace the “OH” functional group with “H” and draw the resulting structure. Name the new compound (reference Chap. 13). NH CH3 HO Pseudoephedrine CH3Laboratory Manual 309 C C Class Functional Group IUPAC ending C C C C R OH C R R O C R H O C R OH O C R OR O R NO2 R NH2 R N R H R N R R Amines Alkane Alkene Alkyne Alcohol Ketone Aldehyde Carboxylic Acid Ester Nitro Compounds "-ane" "-ene" "-yne" "-ol" "-al" "-oic acid" "-amine" "-one" 1o 2o 3o310 Laboratory Manual Experiment # 9 Name ____________________________ Microcrystallography Reference: Chapter 8 Objective: Students will gain experience in the forensic identifi cation of elements using microcrystalline technique. Materials: Solid form and 5% solutions of the following: NH 4 Cl, NaCl, LiCl, ammonium molybdate (AMM-hydrate or anhydrous), and NaOH. 5% solutions of the following: Mg(C 2 H 3 O 2 ) 2 , Mg(NO 3 ) 2 , Na 2 HPO 4 and KMnO 4 (or alternatively, NaMnO 4 ). Acids: 5M HCl and 5M HClO 4 (perchloric acid). Others: KCl (solid), CaCO 3 (sat. solution), and MgO (sat. solution), Microscope, microscope slides, droppers. Solutions : Prepare 5% (m/v) solutions by dissolving 5 g of solid in 100 ml total volume. Alternatively, methanol may be used as solvent, however water forms slightly more stable crystals. KMnO 4 should be prepared fresh. If NaMnO 4 is used instead of KMnO 4 , you will need to add a few drops of H 2 SO 4 (5% v/v) to solution to increase solubility. Part A: Technique 1: Mount a slide on the microscope, place a few crystals of NaCl on the slide using a small spatula, and focus the solid in the microscope. Add a drop of Na 2 HPO 4 solution directly on the solid and observe crystal formation using the microscope without mixing. Record your results below. Repeat with other solids and solutions listed below. Solid Solution Crystals (Yes/No) Sketch Crystals (if yes) NaCl Na 2 HPO 4 NaOH Mg(NO 3 ) 2 KCl HClO 4 AMM HCl LiCl KMnO 4 Conclusion: Part B: Technique 2: Mount a slide on the microscope, place a drop of Na 2 HPO 4 solution on the slide, and focus the drop in the microscope. Add a few crystals of NH 4 Cl to the drop and, without mixing, observe crystal formation using the microscope. Record your results below. Repeat with other solutions and solids listed below. Solids Solutions Crystals (Yes/No) Sketch Crystals (if yes) NH 4 Cl Na 2 HPO 4 NaOH Mg(NO 3 ) 2 KCl HClO 4 AMM HCl LiCl KMnO 4 Conclusion: Laboratory Manual 311 Part C: Micro Test Technique Technique 3: Mount a slide on the microscope, place a drop of solution-I on the slide and focus the drop in the microscope. Add a drop of solution-II to fi rst drop and, without mixing, observe crystal formation using the microscope. Record your results below. Repeat with other solutions listed below. Solutions-I Solutions-II Crystals (Yes/No) Sketch Crystals (if yes) NH 4 Cl Na 2 HPO 4 CaCO 3 Mg(C 2 H 3 O 2 ) 2 MgO HClO 4 Mg(NO 3 ) 2 HCl MgO KMnO 4 Conclusion: Part D: Macro Test Technique Technique 4: Mount a slide on the microscope, place a drop of solution-I on the slide, and focus the drop in the microscope. Add a drop of solution-II to fi rst drop and, without mixing, observe crystal formation using the microscope. Record your results below. Repeat with other solutions listed below. Solution I Solution II Crystals (Yes/No) Sketch Crystals (if yes) NaOH HClO 4 NaCl HClO 4 AMM Na 2 HPO 4 KMnO4 Na 2 HPO 4 LiCl Na 2 HPO 4 Conclusion: 312 Laboratory Manual Experiment # 10 Name ________________________________ Chemical Extraction Reference: Chapter 9 Objective: Students will gain practical experience using forensic extraction techniques to isolate solids from mixtures. Materials: NaHCO 3 (sodium bicarbonate, saturated solution), 0.1 M HCl, starch, aspirin, acetaminophen, H 2 SO 4 (concentrated), formaldehyde, 1% iodine solution acidifi ed with glacial acetic acid, chloroform, hexane, vortex, spot plates, 5 ml test-tubes, droppers, and centrifuge. Prepare a sample mixture containing 100 parts starch:1 part aspirin: 1 part acetaminophen, provide each group with a 1 g sample of the mixture. Part I: Extraction: 1) Place about 0.25 g of sample in a 5 ml test tube labeled “A.” 2) Add 1.0 ml (approx. 20 drops) of 0.1 M HCl. 3) Vortex the mixture and centrifuge. 4) Remove the top liquid using a dropper and place in a clean 5 ml test tube labeled “B.” Be careful not to disturb the solid pellet at the bottom of test tube “A”. 5) Save test tube “A” for Part-II. 6) Add a few drops of NaHCO 3 (sat.) to test tube “B” and vortex the mixture. 7) Add 1.0 ml of hexane and vortex the mixture. 8) Carefully transfer the organic layer using a dropper to a clean test tube labeled “C.” Save test tube “C” for Part-II. The organic layer is hexane and should be the top layer, but check using solubility in DI water. 9) Add 1.0 ml chloroform to test tube “B” and vortex the mixture. 10) Carefully transfer the organic layer using a dropper to a clean test tube labeled “D.” Save test tube “D” for Part-II. The organic layer is chloroform (CHCl 3 ) and should be the bottom layer, but check using solubility in DI water. Part II: Screening Tests: Perform the screening tests below on the samples contained in test tubes A (solid pellet), B (aqueous layer), C (organic layer, hexane), and D (organic layer, chloroform). The best results are obtained when the tests are run side-by-side as opposed to in sequence (reference Chap. 7). Starch test is positive when blue color appears with iodine. Concentrated sulfuric acid and formaldehyde produce red color with aspirin. Test 1: Reference Place a small sample (1/2 pea size) of the original mixture of starch, aspirin, and acetaminophen mixture (100:1:1) into each of two clean, separate wells of a spot plate. These wells will be your reference, so do not empty or clean after the tests are performed. Starch Test: Add one drop of 1% iodine solution to the fi rst well containing the sample and record the color change: _______________. Do not empty or clean the well. Aspirin Test: Add one drop of formaldehyde and three drops of concentrated sulfuric acid to the second well containing the sample and record the color change: __________________________. Do not empty or clean the well. Laboratory Manual 313 Test 2: Place a small amount of solid from test tube “A” into each of two clean, separate wells of the spot plate. Repeat the tests above and record your results. Compare the intensity of the colors produced to the colors in the reference. Result of starch test:___________________________ Result of aspirin test:___________________________ Test 3: Place 3 three drops of solution in test tube “B” into each of two clean, separate wells of the spot plate. Evaporate the solvent and repeat the tests above. Record your results below and compare the relative intensity of the colors produced to the colors in the reference. Result of starch test:___________________________ Result of aspirin test:___________________________ Test 4: Place 3 three drops of solution in test tube “C” into each of two clean, separate wells of the spot plate. Evaporate the solvent and repeat the tests above. Record your results below and compare the relative intensity of the colors produced to the colors in the reference. Result of starch test:___________________________ Result of aspirin test:___________________________ Test 5: Place 3 three drops of solution in test tube “D” into each of two clean, separate wells of the spot plate. Evaporate the solvent and repeat the tests above. Record your results below and compare the relative intensity of the colors produced to the colors in the reference. Result of starch test::___________________________ Result of aspirin test:___________________________ Summarize your conclusions based on the test results: 314 Laboratory Manual Experiment # 11 Name ___________________________________ Chromatography Reference: Chapter 10 Objective: Students gain practical experience using paper chromatography to separate the components of a variety of mixtures. Materials: Red, blue, green, brown, and black felt tip pens, chromatographic paper, 1-butanol, 1-propanol, saran wrap. Introduction: Chromatography is a technique that utilizes a stationary phase and a mobile phase to separate the components of a mixture. The separation process is based on the fact that a given component (molecule) will exhibit a higher affi nity for one of the phases and will either move in the mobile phase or remain in place on the stationary phase. Affi nity is infl uenced by several factors, but size and polarity often play key roles. In this experiment, paper chromatography will be used to separate the components of ink commonly found in felt-tipped pens. The mixture (ink) will be spotted on the chromatographic paper (stationary phase) and placed in a developing chamber containing the mobile phase (solvent mixture). The mobile phase will migrate up the paper and contact each of the ink mixtures. The components in the ink that are soluble in the mobile phase will move up the stationary phase (paper) at different rates depending on size and polarity. The components that are not soluble will remain in place on the stationary phase. There are many types of chromatographic techniques and several factors must be considered when choosing a particular method. Thin-layer chromatography (TLC), for example, is simple, quick, and relatively inexpensive; however, it provides only qualitative results. High-performance liquid chromatography (HPLC) is more complex and requires sophisticated instrumentation, but it provides extremely accurate quantitative results. Other forms of chromatography include column chromatography, liquid chromatography (LC), and gas chromatography (GC). Procedure: 1. Place 15.0 mL of 1-propanol, 15.0 mL of 1-butanol, and 15.0 mL of deionized water in a clean, dry 600 ml beaker. Cover the top of the beaker tightly with saran wrap. A rubber band may be used to secure the plastic wrapping. Lightly swirl the beaker to mix the contents. This will be used as the developing chamber. 2. Obtain a 10 cm × 15 cm piece of chromatographic paper. Handle the chromatographic paper using the edges at all times . Touching the paper with bare hands may deposit oils and dirt that will affect your results. 3. Using a ruler and a lead pencil, draw a straight line across the entire 10 cm width, 1.5 cm up from the bottom edge of the paper. Do not use a pen to draw this line . 4. Mark fi ve small dots on the line with a pencil at 1.5 cm intervals. 5. Spot each dot with a different colored pen and allow the spots to dry. 6. Remove the saran wrap cover on the developing chamber and carefully place the chromatographic paper in the beaker with the edge nearest the samples placed downward in the solvent (handle the paper using the edges only). Important : Be sure that the samples are NOT immersed in the solvent. Replace the saran wrap cover. Laboratory Manual 315 7. The developing solvent will begin to migrate up the paper. Allow the system to stand undisturbed until the solvent has run close to the top of the paper, or for a period of 60 min. Do not allow the solvent to reach the top of the paper. 8. Remove the paper from the developing chamber and draw a line across the solvent front using a pencil. Allow the paper to dry. 9. Answer the following questions: (a) What colors have properties similar to the solvent? (b) What colors have properties that are different from the solvent? (c) What pens contain components that are similar? (d) How many components are contained in the red ink? (e) How many components are contained in the blue ink? (f) How many components are contained in the black ink? (g) What components appear to be common in the pens tested? (h) Do you believe your results would be different if ink pens from another manufacturer were used? Explain. 316 Laboratory Manual Experiment # 12 Name _______________________________ GCMS Interpretation Reference: Chapter 10 Objective: Students will gain experience in the interpretation of data provided by GCMS analysis. Introduction: Gas chromatography (GC) can be combined with mass spectrometry (MS) to provide scientists with an extremely valuable technique used to identify the components present in a gaseous mixture (GCMS). A sample of the mixture under analysis is injected into the gas chromatograph where it is immediately vaporized in the injection port. A carrier gas (mobile phase, usually N 2 or He) passes the vaporized sample through a column contained in the GC (stationary phase). The individual components in the gaseous mixture interact with the column to accomplish separation. In gas chromatography, the separation process is usually size dependent; smaller molecules interact less with the column and arrive at the detector faster than larger ones. The time required for a particular component to travel from the injection port to the detector is called the retention time . Retention times are basically the time each component spends in the column and are specifi c to that component. The detector records each component eluting off the column as a peak on a chromatogram at specifi c retention times. Although a GC does not routinely provide quantitative data, it does give important information about the components in a gaseous mixture. Since each component is recorded as a peak on the chromatogram, the number of components present in the mixture is easily determined by simply counting the number of observable peaks. Most modern GCs are automated and contain software that calculates the area under each peak. These calculations are used to determine the relative amounts of each component. For example, if the area under one peak is twice the area under another, that component is present in twice the quantity. The exact amounts are not known, but the relative concentrations are. Retention times can be used to determine the relative size of each component present. Peaks observed at low retention times represent smaller molecules, while those with greater times represent larger ones. Once again, the actual size of each component is not known, but the relative sizes are easily determined. The identity of each component is determined through mass spectrometry. The separated components from GC are passed into a mass spectrometer coupled directly to the GC. In the mass spectrometer, each component is bombarded with a beam of high-energy electrons that fragment the molecule into positively charged ions. The fragmented ions are recorded on a mass spectrum by mass (specifi cally charge/mass). The base peak is the most intense (highest) and represents the base ion ; usually the most stable ion formed (the one formed the easiest). The base peak is assigned 100% and the intensities of the other peaks are recorded as percentages of the base peak. Tables identifying ions of specifi c mass are used to reassemble the molecule from the ion fragments. The base peak and the molecular ion peak often play key roles in the identifi cation process. The molecular ion is formed when a single electron is ejected from the molecule by the imposed highenergy beam. This peak commonly represents the mass of the molecule under investigation. In some cases, the molecular ion may be the base peak; however, this is not a requirement and should not be considered a standard. Laboratory Manual 317 Part A: Interpret the gas chromatogram below and answer the following questions. 1. Identify each component in the mixture using retention times. How many different components are present? (Hint: peaks below Abundance 1000000 are not considered components). 2. Identify the peak representing the component of smallest mass. 3. Identify the peak representing the component of greatest mass. 4. Predict the peak representing the molecule present in greatest abundance. 5. Predict the peak representing the molecule present in least abundance. Part B: Identify each of the following using the MS data provided. You will need to reference additional information from your text. Name Molecular Ion (m/z) Base Ion (m/z) Other Prominent Ions 1) 135 044 91, 92, 65, 120, 134, 77 2) 303 082 182, 83, 77, 94, 105 3) 369 327 268, 204, 310, 315 4) 237 180 182, 209, 152, 138 5) 243 200 91, 242, 243, 186 318 Laboratory Manual Part C: List the mass (m/z) of the major ion fragments formed from each the following. Draw the structure of each fragment. 1) Methamphetamine: 2) MDMA: 3) Psilocin/psilocybin: 4) THC: 5) Pseudoephedrine: Laboratory Manual 319 Part D: Draw the ion fragments represented in the MS data provided for each of the following molecules. CH3 NH2 O O N N O C2H5 C2H5 CH3 N H H HN H O N O O CH2 MDA Molecular weight = 179 Base peak = 44 Prominant peaks: 51, 77, 81, 135, 136 CH H3C CH3 CH2 Molecular weight = 323 Base peak = 221 Prominant peaks: 72, 167, 181, 196, 207 CH2 CH Butalbital Molecular weight = 244 Base peak = 168 Prominant peaks: 97, 124, 141, 153, 167, 181320 Laboratory Manual Experiment # 13 Name ______________________ IR Spectroscopy Reference: Chapter 11 Objective: The student will gain experience in the interpretation of infrared spectra. Introduction: Spectroscopy is the study of the interaction of atoms and molecules with electromagnetic radiation. These interactions often involve the emission or absorption of discrete amounts of energy, which is detected using analytical instrumentation. When energy, in the form of infrared radiation (IR), is absorbed by a particular substance, it produces measurable affects that are detected using an infrared spectrometer . Infrared radiation is a low energy form of radiation that is best described as “heat.” When we feel the warmth of the sun, we are actually responding to infrared radiation. The heat emitted from the sun is absorbed by our bodies and stimulates molecules in our skin to vibrate. We interpret this vibrational energy as “warmth.” A similar activity is observed in molecules. When infrared radiation is absorbed by a molecule, the chemical bonds convert the energy into molecular vibrations. IR spectroscopy measures the frequency of the radiation absorbed by a particular bond and records this as a band on an infrared spectrum . Tables containing bond vibrational frequencies are used to identify the bond from the absorption bands observed on the spectrum. The location of absorption bands on spectra are commonly represented in units of wavenumbers or wavelengths . The wavenumber unit (cm -1 , reciprocal centimeters) is used most often because it is directly proportional to vibrational energy and most modern spectrometers are linear in the wavenumber scale. Identifi cation of a molecule based solely on an infrared spectrum is rare because IR spectroscopy is used to identify specifi c bonds in a molecule . For example, a carbonyl group (carbon–oxygen double bond) is easily identifi ed by a characteristic absorption band present on the spectrum; however, ketones, aldehydes, carboxylic acids, and esters all contain a carbonyl group. Therefore, absolute confi rmation of identity will require information from other analytical methods. Nonetheless, IR spectroscopy is often an important source of supporting evidence in the identifi cation process. Part A: The IR spectrum of cocaine base and cocaine HCl are provided. Compare the two spectra and identify absorption bands common to both and those distinct to each spectrum (uncommon bands). Identify each band using wavenumber region and record your observations in the table below. Laboratory Manual 321 Wavenumbers (cm -1 ) Common Bands Distinct Bands Cocaine HCl Cocaine Base 322 Laboratory Manual Part B: The IR spectrum of ephedrine and pseudoephedrine are provided. Compare the two spectra and identify absorption bands common to both and those distinct to each spectrum (uncommon bands). Identify each band using wavenumber region and record your observations in the table below. Wavenumbers (cm -1 ) Common Bands Distinct Bands Ephedrine Pseudoephedrine Laboratory Manual 323 Experiment # 14 Name ______________________ Examination of Marijuana (moot) Reference: Chapter 12 Objectives : The student will gain experience in the forensic identifi cation of marijuana plants. A report of fi ndings will also be written and presented. A plant material case submission contains following information/evidence. Visual Inspection: Microscopic Investigation:324 Laboratory Manual Chemical Investigation: Duquenois-Levine test results Questions: 1. Describe the physical characteristics of the leaves based on visual inspection. 2. Describe the physical characteristics of the seeds based on visual inspection. 3. Describe your observations from microscopic investigation. What types of hairs are visible? 4. The Duquenois-Levine test was performed as part of the chemical investigation. (a) What reagents are found in the top layer of the Duquenois-Levine test? (b) What reagents are found in the bottom layer of the Duquenois-Levine test? (c) What is the result of the Duquenois-Levine test? 5. What conclusions can be made based on your results in this investigation? Laboratory Manual 325 Experiment # 15 Name ___________________________________ Examination of Controlled Substances: Primary and Secondary Amines (moot) Reference: Chapter 13 Objective: Students will gain experience in the forensic identifi cation of controlled substances classifi ed as primary and secondary amines using case data. You are provided forensic data for three separate examination scenarios. Carefully study the information and predict the controlled substance(s) in each profi le. Write a report of your fi ndings. Part A: White Crystals: Mass Spectrum: 326 Laboratory Manual Questions: 1. Name the color-screening tests that you would perform in this case. 2. Predict the results of the screening tests in question 1. 3. Describe the method you would use as a confi rmatory examination. 4. What type of extraction would be performed to prepare a sample for GCMS analysis? 5. Identify the controlled substance and provide supporting data for your conclusion. Part B: Red Tablets Mass Spectrum Questions: 1. Name the color-screening tests that you would perform in this case. 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. Laboratory Manual 327 Part C: Light Brown Powder Mass Spectrum Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. What type of extraction would you perform to prepare a sample for GCMS analysis? 5. Identify the controlled substance and provide supporting data for your conclusion. 328 Laboratory Manual Experiment # 16 Name _______________________________ Examination of Controlled Substances: Tertiary Amines and Opiates (moot) Reference: Chapter 14 Objective: Students will gain experience in the forensic identifi cation of the tertiary amine class of controlled substances using case data provided. You are provided forensic data for three separate examination scenarios. Carefully study the information and predict the controlled substance(s) in each profi le. Write a report of your fi ndings. Part A: Chunks of Tan/White Substance IR Spectrum Laboratory Manual 329 Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. Part B: Black Chunk Mass Spectrum 330 Laboratory Manual Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. Part C: Stained Cigarette and Yellow Oil GCMS spectra Laboratory Manual 331 Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. 332 Laboratory Manual Experiment # 17 Name ______________________ Examination of Controlled Substances: Tryptamines (moot) Reference: Chapter 15 Objective: Students will gain experience in the forensic identifi cation of the tryptamine class of controlled substances. You are provided forensic data for three separate examination scenarios. Carefully study the information and predict the controlled substance(s) in each profi le. Write a report of your fi ndings. Part A: Mushrooms Results of Thin-Layer Chromatography (TLC) Laboratory Manual 333 Mass Spectrum: Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. Part B: Plant Material 334 Laboratory Manual Mass Spectrum: Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. Laboratory Manual 335 Experiment # 18 Name ______________________ Examination of Anabolic Steroids (moot) Reference: Chapter 16 Objective: Students will be exposed to the forensic identifi cation of anabolic steroids. You are provided forensic data for three separate examination scenarios. Carefully study the information and predict the controlled substance(s) in each profi le. Write a report of your fi ndings. Part A: Red Capsules Mass Spectrum Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. 336 Laboratory Manual Part B: Injection Vial Mass Spectrum: Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. Part C: Tablets Laboratory Manual 337 Mass Spectrum: Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. 338 Laboratory Manual Experiment # 19 Name ________________________________ Examination of Miscellaneous Controlled Substances (moot) Reference: Chapter 17 Objective: Students will gain experience in the forensic identifi cation of various functional groups present in different controlled substances. You are provided forensic data for three separate examination scenarios. Carefully study the information and predict the controlled substance(s) in each profi le. Write a report of your fi ndings. Part A: Paper Tabs GSMS Spectra Laboratory Manual 339 Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. Part B: Capsules Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. Part C: Tablets 340 Laboratory Manual Mass Spectrum: Questions: 1. What color-screening tests would you perform in this case? 2. Predict the results of the screening tests in question 1. 3. Describe the confi rmatory method that you would use to identify this substance. 4. Identify the controlled substance and provide supporting data for your conclusion. Laboratory Manual 341 Experiment # 20 Name ______________________ Clandestine Manufacturing of Methamphetamine (moot) Reference: Chapters 18, 19, and 20 Objectives: Students will gain experience in the forensic identifi cation of case evidence collected at clandestine lab sites. This will be extended to include the association of distinctive evidence to specifi c synthetic steps used in the illegal production of methamphetamine. Carefully study the photographs below and answer the following questions based on your observations. You will need to refer to your text. 1. Identify the method used in the production of methamphetamine. Justify your answer. 2. What chemicals are required for the method in question 1? 3. List the synthetic steps used in the production of methamphetamine using this method. 4. What synthetic step is indicated by the evidence shown in photograph 1? 5. List the chemical(s) required to prove this step. 342 Laboratory Manual 6. Briefl y outline the procedure you would use in the forensic examination of the evidence shown in photograph 1. 7. Summarize your conclusion on this piece of evidence. 8. What synthetic step is indicated by the evidence shown in photograph 2? 9. List the chemical(s) required to prove this step. 10. Briefl y outline the procedure you would use in the forensic examination of the evidence shown in photograph 2. 11. Summarize your conclusion on this piece of evidence. 12. What synthetic step is indicated by the evidence shown in photograph 3? 13. List the chemical(s) required to prove this step. 14. Briefl y outline the procedure you would use in the forensic examination of the evidence shown in photograph 3. 15. Summarize your conclusion on this piece of evidence. 16. What synthetic step is indicated by the evidence shown in photograph 4? Laboratory Manual 343 17. List the chemical(s) required to prove this step. 18. Briefl y outline the procedure you would use in the forensic examination of the evidence shown in photograph 4. 19. Summarize your conclusion on this piece of evidence.