Allen Independent School District / Overview



IB Chem: Analytical Chemistry ReviewReview for the Modern Analytical Chemistry:You should be able to: describe the equipment and procedures used for the analysis of substances using atomic absorption (AA) spectrometry, infrared (IR) spectroscopy, mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy describe how the structure of compounds may be deduced using information obtained from various spectroscopic techniques analyse IR, mass and NMR spectra in order to gain information about molecular structure understand that all chromatographic techniques require a stationary phase and a mobile phase describe how chromatography is used to identify and quantify the components of a mixture use a calibration curve in quantitative chromatographic and spectroscopic analysis calculate Rf values and describe the significance of Rfand Rt values in chromatography describe the equipment and procedures used for the analysis of substances by paper, thin-layer and column chromatography recognize that chromatographic techniques can be used to separate components of a mixture prior to analysis by other techniques such as mass spectrometry and IR spectroscopy describe the equipment and procedures used for the analysis of substances using gas and high performance liquid chromatography describe the equipment and procedures used for the analysis of substances using UV–visible spectrometry analyse UV–visible spectra in order to gain information about molecular structure interpret splitting patterns (HL) and chemical shifts in NMR spectra to gain information about molecular structure. Review for Medicines and Drugs:You should be able to: describe general aspects of medicines and drugs such as their effects, methods of administration, terminology and the stages involved in research and development of new drugs discuss the use of antacids for treating excess acidity in the stomach compare the use, effects and structures of strong and mild analgesics compare the use, effects and structures of depressants, including ethanol describe the techniques used for the detection of ethanol in breath, blood and urine compare the use, effects and structures of stimulants, including nicotine and caffeine discuss the history, structure, method of function and effect of overprescription of penicillins as an example of antibacterial medicines state how viruses differ from bacteria, and describe the different ways in which antiviral drugs work discuss the difficulties related to the spread of AIDS and the solution to this worldwide problem discuss and explain the importance of structural features such as chirality and geometric isomerism in the action of drugs describe aspects of drug design such as compound libraries, combinatorial chemistry, computer modelling, structural modification and chiral auxiliaries describe the effects and structural similarities and differences of the mind-altering drugs LSD, mescaline, psilocybin and THC discuss the legalization of cannabis. IB Chemistry – Analytical anic compounds are often identified by using more than one analytical technique. Some of these techniques were used to identify the compounds in the following reactions.C3H7Br→ C3H8O→ C3H6O A BC(a)Using H2O as an example, describe what happens, at a molecular level, during the absorption of infrared radiation. (3)(b)The infrared spectrum of B showed a broad absorption at 3350 cm–1. The infrared spectrum of C did not show this absorption, but instead showed an absorption at 1720 cm–1. Explain what these results indicate about the structures of B and C. (2)(c)The mass spectrum of A showed two lines of approximately equal height, one of which was at m/z = 122. State the m/z value of the other line and explain these observations. (3)(d)The evidence in (b) and (c) indicates that each compound (A, B and C) could have two possible structures. Draw the two possible structures of C.(2)(e)Fragmentation of C in a mass spectrometer produced lines with m/z values of 15 and 28, but none at values of 14 or 29. Identify C and explain how you used this information to do so.(2)(f)State the number of lines in the 1HNMR spectrum of each of the structures in (d). (2)2.A student used the technique of ascending paper chromatography in an experiment to investigate some permitted food dyes(labelled P1 - P5). The result is shown below.(a)By reference to the diagram above, describe how the experiment would be carried out and explain the meaning of the terms stationary phase, mobile phase, partition, solvent front and Rf value.(8)(b)(i)Calculate the Rf value of P1. (2)(ii)State, giving a reason, whether P4 is a single substance or a mixture.(1)3.Explain the following observation: Phenolphthalein is colourless in acidic solutions but coloured in alkaline solutions.(2)4.A student wanted to determine a more accurate value for the concentration of a solution of Mn2+ (aq) which was known to be between 0.10 and 0.010 mol dm–3. She was provided with a solution of 1.00 mol dm?3 manganese(II) sulfate, MnSO4. Describe how she could determine the unknown concentration using a visible spectrometer and explain the importance of the Beer-Lambert law in the method used.(5)5.Describe the IR and 1H NMR spectra of propanal and propanone. Your answer should include both the similarities and the differences between the spectra of both compounds. (Total 8 marks)6.(a)All chromatographic techniques involve the phenomena of adsorption or partition. They all use a stationary phase and a mobile phase, but these phases can include solids, liquids or gases. Complete the following table to show which states of matter are used in the two phenomena. Stationary phaseMobile phaseAdsorption Partition (3)(b)Explain the term Rf value used in some chromatographic techniques. (1)(c)Outline how the technique of column chromatography could be used to separate a mixture?of two coloured substances in solution. (4)(Total 8 marks)7.The mass spectra of halogenoalkanes show more than one line corresponding to the molecular ion. This is due to the presence of isotopes such as 35Cl, 37Cl, 79Br and 81Br.(a)Analyse the following spectra of halogenoalkanes P and Q and deduce the formula of all the molecular ion species.[Source: NIST Mass Spec Data Center, S E Stein, director, “IR and Mass Spectra” in NIST Chemistry WebBook, NIST Standard Reference Database Number 69, Eds. P J Linstrom and W G Mallard, July 2001, National Institute of Standards and Technology, Gaithersburg MD, 20899 ()]species in P ..................................................................................................................species in Q .................................................................................................................(3)(b)Predict the m/z values of the molecular ions for the compounds C2H5Br and C2H4Cl2 C2H5Br ......................................................................................................C2H4Cl2 ...................................................................................................... (2) 8.(a)Draw structures for two possible isomers of a compound with the formula C2H4O2. (2)(b)The infrared spectrum of this compound shows the following absorptions: 2920, 2765 and 1710cm?1 . Use the information in Table 18 of the Data Booklet to assign each absorption to a particular vibration.(2)(c)Deduce the structure from (a) which would demonstrate the infrared absorptions above. Explain your answer. (2)9.(a)1H NMR spectroscopy can be used to obtain information about the structure of molecules.State the information that can be obtained from the(i)number of peaks.(1)(ii)chemical shift. (1)(iii)ratio of peak areas. (1)(iv)splitting pattern. (1)(b)The 1HNMR spectrum of a compound with the formula C4H8O2 with chemical shifts, areas?and splitting patterns given below exhibits three major?peaks.chemical shift / ppmpeak areasplitting pattern0.93triplet2.02quartet4.13singletUsing information from Table 19 in the Data Booklet, determine the types of proton present in the molecule. (3)(c)Deduce a structure consistent with the information indicated in (b). Explain your answer.(5)Medicines and Drugs Practice Test Questions1.(a)Many drugs are taken orally. State three other ways in which drugs may be taken by a patient.……………………………………………………………………………………….……………………………………………………………………………………….(2)(b)State what is meant by the term side effect.……………………………………………………………………………………….……………………………………………………………………………………….(1)2.One common type of drug taken orally is the antacid. Antacids such as sodium hydrogencarbonate are taken to reduce stomach acidity.(i)State the names of two metals, other than sodium, whose compounds are often used in antacids.………………………………………………………………………………………….(1)(ii)Give an equation for the neutralization of hydrochloric acid in the stomach by sodium hydrogencarbonate.…………………………………………………………………………………………(1)(iii)Explain how heartburn is caused.…………………………………………………………………………………………..…………………………………………………………………………………………..(1)(iv)Explain why dimethicone is added to some antacids.…………………………………………………………………………………………..(1)3.Morphine is a naturally occurring analgesic that can be converted into codeine.(i)Calculate the difference in relative formula mass between morphine and codeine.…………………………………………………………………………………………..…………………………………………………………………………………………..(1)(ii)Explain what is meant by developing tolerance towards codeine and state why this is dangerous.…………………………………………………………………………………………..…………………………………………………………………………………………..…………………………………………………………………………………………..(2)4.The breathalyser can be used to detect ethanol in breath. Explain how this can be done, by reference to the substance used, the colour change and the type of reaction occurring.…………………………………………………………………………………………..…………………………………………………………………………………………..…………………………………………………………………………………………..(3)5.The structures of some analgesics are shown in Table 21 of the Data Booklet.Refer to this table when answering parts (b) and (c) of this question.(a)Explain the difference in the method of action of mild analgesics and strong analgesics..........................................................................................................................................................................................................................................................................(2)(b)State the name of the nitrogen-containing functional group in each of the following molecules.Paracetamol ................................................................................................................Heroin .........................................................................................................................(2)(c)Naturally-occurring morphine can be converted into synthetic heroin by reaction with ethanoic acid. Identify the group in the morphine molecule that reacts with ethanoic acid, the name of the type of reaction and the other product of the reaction.Group in morphine molecule .......................................................................................Type of reaction ...........................................................................................................Other product of reaction .............................................................................................(3) ................
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