- Basic information
Basic information
Introduction There are seven options and students must answer questions on two of them in Paper 3 of the examination. For most teachers this means teaching two of the options to their students - 15 hours each for Standard Level and 22 hours each for Higher Level. Thus each option has 15 hours of common SL/HL material divided into sub-topics together with an additional 7 hours of extension material for Higher Level students. If you do the sums you will see that the options constitute 30 of the 110 hours - Option A
Option A
Introduction For me Option A hits all the right buttons. It is relevant to students who are not progressing further with science after they complete their Diploma as they will often come across references to it throughout their lives. These may include newspaper articles on the latest athlete to fail a drug test (below left) or a forensic report in a sensational murder trial or more mundanely when they go into hospital themselves for an MRI scan (below right). For the student who is going on to university to study- Techniques & principles
Techniques & principles
A1 & A2 Analytical techniques & principles of spectroscopy (3h) Aims State the reasons for using analytical techniques and state that the structure of a compound can be determined by using information from a variety of techniques either singly or in combination. Describe the electromagnetic spectrum. Distinguish between absorption and emission spectra and how each is produced. Describe the atomic and molecular processes in which absorption of energy takes place. Clarification notes Include structural determination, analysis of composition of substances and purity. Usually a combination of techniques is - Infrared spectroscopy
Infrared spectroscopy
A3 Theory and applications of IR spectroscopy (3h) Aims Describe the operating principles of a double-beam IR spectrometer Describe how information from an IR spectrum can be used to identify bonds. Explain what occurs at a molecular level during the absorption of IR radiation by molecules. Analyse IR spectra of organic compounds. Clarification notes A schematic diagram of a double-beam spectrometer is all that is needed. Use H2O, -CH2-, SO2 and CO2 as examples. Need to stress that a change in dipole moment (i.e. bond polarity) as - Mass spectrometry
Mass spectrometry
A4 Theory and applications of mass spectroscopy (2h) Aims Revise/review Topic 2.2 - The mass spectrometer. Determine the molecular mass of a compound from the molecular ion peak, M+. Analyse fragmentation patterns in a mass spectrum to find the structure of a compound. Clarification notes Students need to know the stages of how a mass spectrometer works and how it can be used to measure relative masses of atoms based on 12C scale and be able to calculate relative atomic masses based on abundance of isotopes. - 1H NMR spectroscopy (1)
1H NMR spectroscopy (1)
A5 Theory and applications of 1H NMR spectroscopy (2h) Aims Enable students to be able to deduce the structure of a compound from its low resolution 1H NMR. Outline how NMR (Magnetic Resonance Imaging) is used in body scanners. Clarification notes There is no mention on the syllabus of the theory behind NMR. There is also no specific mention of chemical shift and the use of TMS. Students need to know about the number of different chemical environments for hydrogen atoms within a molecule and the relative number of- Isomers of bromobutane
Isomers of bromobutane
Using 1H NMR to identify the isomers of bromobutane One of the real strength of 1H NMR is that it enables students to distinguish quickly between isomers. The four structural isomers of bromobutane, C4H9Br often appear on examination papers as they provide an excellent example for problems on NMR. A similar example can be found with the isomers of butanol, C4H10O. I've set this up as a PowerPoint presentation that you might like to use but to get the best out of it it might help if I put the - NMR questions (1)
NMR questions (1)
Questions on 1H NMR spectroscopy 1. Solid organic compounds are often dissolved in trichloromethane before they are analysed by 1H NMR spectroscopy. Explain why the solvent must be deuterated trichloromethane, CDCl3, and not ordinary trichloromethane CHCl3. 2. Identify the number of peaks and the area under each peak that will appear in the 1H NMR spectra of: (a) methane (b) ethane (c) propane (d) ethanoic acid (e) propanoic acid 3. There are four structural isomers of C4H10Br. They are: 1-bromobutane 2-bromobutane 1-bromo-2-methylpropane and 2-bromo-2-methylpropane. For each of the four
- Isomers of bromobutane
- Spectroscopy questions
Spectroscopy questions
The strength of combining different techniques Each spectroscopic technique in itself may not provide enough information to determine unambiguously the identity of a compound but taken together they are a very powerful tool. Students usually very much enjoy the challenge presented by the following ten questions. In each question they will first need to use the elemental analysis data to work out the empirical formula of the compound. From the m/z value (the mass spectra actually label this m/e value) for the molecular ion, M+ they can determine the molar- Question 1
Question 1
Option A Spectroscopy Question 1 Identify compound A from the data (a – d) given and explain how you arrived at your answer a) Elemental analysis of compound A Element Percentage by mass Carbon 24.3 Hydrogen 4.1 Chlorine 71.6 b) Mass spectrum of compound A c) Infrared spectrum of compound A d) Information about compound A from 1H NMR spectrum Position of peak / δ ppm Integration trace 2.0 3 5.8 1 Download the Spectroscopy question (1) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest ratio Carbon 24.3/12.01 - Question 2
Question 2
Option A Spectroscopy Question 2 Identify compound B from the data (a – d) given and explain how you arrived at your answer a) Elemental analysis of compound B Element Percentage by mass Carbon 15.40 Hydrogen 3.24 Iodine 81.36 b) Mass spectrum of compound B c) Infrared spectrum of compound B d) Information about compound B from 1H NMR spectrum Position of peak / δ ppm Integration trace 1.8 3 3.1 2 Download the Spectroscopy question (2) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest ratio - Question 3
Question 3
Option A Spectroscopy Question 3 Identify compound C from the data (a – d) given and explain how you arrived at your answer a) Elemental analysis of compound C Element Percentage by mass Carbon 66.61 Hydrogen 11.20 Oxygen 22.19 b) Mass spectrum of compound C c) Infrared spectrum of compound C d) Information about compound C from 1H NMR spectrum Position of peak / δ ppm Integration trace 0.9 3 2.0 3 2.3 2 Download the Spectroscopy question (3) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest ratio - Question 4
Question 4
Option A Spectroscopy Question 4 Identify compound D from the data (a – d) given and explain how you arrived at your answer a) Elemental analysis of compound D Element Percentage by mass Carbon 29.29 Hydrogen 5.75 Bromine 64.96 b) Mass spectrum of compound D c) Infrared spectrum of compound D d) Information about compound D from 1H NMR spectrum Position of peak / δ ppm Integration trace 1.7 6 4.3 1 Download the Spectroscopy question (4) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest ratio Carbon - Question 5
Question 5
Option A Spectroscopy Question 5 Identify compound E from the data (a – d) given and explain how you arrived at your answer a) Elemental analysis of compound E Element Percentage by mass Carbon 54.52 Hydrogen 9.17 Oxygen 36.31 b) Mass spectrum of compound E c) Infrared spectrum of compound E d) Information about compound E from 1H NMR spectrum Position of peak / δ ppm Integration trace 1.2 3 2.0 3 4.2 2 Download the Spectroscopy question (5) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest - Question 6
Question 6
Option A Spectroscopy Question 6 Identify compound F from the data (a – d) given and explain how you arrived at your answer a) Elemental analysis of compound F Element Percentage by mass Carbon 48.63 Hydrogen 8.18 Oxygen 43.19 b) Mass spectrum of compound F c) Infrared spectrum of compound F d) Information about compound F from 1H NMR spectrum Position of peak / δ ppm Integration trace 1.1 3 2.4 2 11.1 1 Download the Spectroscopy question (6) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest - Question 7
Question 7
Option A Spectroscopy Question 7 Identify compound G from the data (a – d) given and explain how you arrived at your answer a) Elemental analysis of compound G. Element Percentage by mass Carbon 28.76 Hydrogen 4.23 Oxygen 19.16 Bromine 47.85 b) Mass spectrum of compound G c) Infrared spectrum of compound G d) 1H NMR spectrum of compound G Download the Spectroscopy question (7) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest ratio Carbon 28.76/12.01 = 2.39 4 Hydrogen 4.23 / 1.01 - Question 8
Question 8
Option A Spectroscopy Question 8 Identify compound H from the data (a – d) given and explain how you arrived at your answer. a) Elemental analysis of compound H Element Percentage by mass Carbon 80.56 Hydrogen 7.52 Oxygen 11.92 b) Mass spectrum of compound H c) Infrared spectrum of compound H d) 1H NMR spectrum of compound H Download the Spectroscopy question (8) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest ratio Carbon 80.56/12.01 = 6.71 9 Hydrogen 7.52 / 1.01 - Question 9
Question 9
Option A Spectroscopy Question 9 Identify compound I from the data (a – d) given and explain how you arrived at your answer. a) Elemental analysis of compound I Element Percentage by mass Carbon 68.11 Hydrogen 13.74 Oxygen 18.15 b) Mass spectrum of compound I c) Infrared spectrum of compound I d) 1H NMR spectrum of compound I Download the Spectroscopy question (9) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest ratio Carbon 68.11/12.01 = 5.67 5 Hydrogen 13.74 / 1.01 = 13.60 12 - Question 10
Question 10
Option A Spectroscopy Question 10 Identify compound J from the data (a – d) given and explain how you arrived at your answer. a) Elemental analysis of compound J Element Percentage by mass Carbon 54.52 Hydrogen 9.17 Oxygen 36.31 b) Mass spectrum of compound J c) Infrared spectrum of compound J d) 1H NMR spectrum of compound J Download the Spectroscopy question (10) to give to students Answer a) From the elemental analysis Element Amount / mol Simplest ratio Carbon 54.52/12.01 = 4.54 2 Hydrogen 9.17 / 1.01 = 9.08
- Question 1
- Atomic absorption
Atomic absorption
A6 Atomic absorption spectroscopy (3h) Aims State the uses of atomic absorption spectroscopy (AA). Describe the principles and uses of components of AA Determine the concentration of a solution from a calibration curve Clarification notes Include the identification of small amounts of metals in water, blood, soil and food. Include the use of the fuel, atomizer, monochromatic light source, monochromatic detector and read-out. Stress the importance of the Beer-Lambert Law and the need for sufficient data. Teaching tips: Start by reviewing topic 2.3 and emission spectra. - Chromatography (1)
Chromatography (1)
A7 Chromatography (paper, thin-layer & column) (2h) Two of my students testing the purity of a product they have prepared using thin-layer chromatography. Aims State the reasons for using chromatography. Explain the principles of chromatography. Outline the uses of paper chromatography, thin-layer chromatography (TLC) and column chromatography (CC). Clarification notes Include qualitative and quantitative aspects. All chromatographic techniques involve adsorption on a stationary phase and partition between a stationary phase and a mobile phase, Different components have different tendencies to absorb onto a surface or dissolve - UV-VIS spectroscopy
UV-VIS spectroscopy
A8 Visible and ultraviolet spectroscopy (3h) Aims Describe the effect of different ligands on the splitting of the d orbitals in transition metal complexes. Describe the factors which affect the colour of transition metal complexes. State that organic compounds with a double bond absorb UV light. Describe the effects of conjugation on the wavelength of absorbed light. Predict whether a particular molecule will absorb UV or visible light. Determine the concentration of a solution using a calibration curve and the Beer-Lambert law. Clarification notes Include - 1H NMR spectroscopy (2)
1H NMR spectroscopy (2)
A9 Theory and applications of 1H NMR spectroscopy (2) (2h) Aims Explain the reasons for using tetramethylsilane as a reference Analyse 1H NMR spectra Clarification notes TMS used because: All 12 protons are in the same chemical environment. Not toxic and is unreactive so does not interfere with sample. Absorbs upfield away from most other protons. Volatile so can easily be removed afterwards. Include: Number of peaks Area under each peak Chemical shift Splitting pattern (singlet, doublet, triplet & quartet) (Coupling constants not required) Teaching tips: This - Chromatography (2)
Chromatography (2)
A10 Chromatography (gas-liquid & HPLC) (2h) Aims Describe the techniques of GLC and HPLC. Deduce which chromatographic technique is most suitable for separating the components in a particular mixture . Clarification notes Include an outline of the operation for each technique. Include Rf values and other relevant factors. HPLC is used for compounds that decompose when heated. GLC used for compounds that vaporise easily. HPLC: Analysis of oil, alcoholic beverages, antioxidants, sugars and vitamins in food, pharmaceuticals, polymers, insecticides and pesticides etc. GLC: Analysis of urine samples
- Techniques & principles
- Option B
Option B
Introduction Teenagers have a natural curiosity about who they are and how their body functions. They want to know the answers to questions like, ‘How do contraceptive pills work?’ ‘How can genetic information be stored in DNA?’ and ‘Why do fatty foods increase the risk of heart disease?’ Option B contains the answers to all these questions and many more. It is one of the more popular options and students generally enjoy studying it as they can very easily relate to the material it covers. Although some of the content- Energy
Energy
B1 Energy (0.5h) Aims Calculate energy values for a food Use enthalpy of combustion data Clarification notes This topic builds on Topic 5.2 calculation of enthalpy changes and no extra theory is really involved. It does not actually spell it out in the syllabus but students should be familiar with the workings of a food calorimeter. Teaching tips: This is quite a nice introduction to Human Biochemistry. I usually start by looking at the average daily energy requirements needed for a healthy female (8400 kJ) and male - Proteins
Proteins
B2 Proteins (3h) Aims Draw the general formulas for 2-amino acids and describe their properties. Describe the condensation of 2-amino acids to form polypeptides. Describe the primary, secondary , tertiary and quartenary structure of proteins. Explain the use of chromatography and electrophoresis to analyse proteins. List the major functions of proteins in the body. Clarification notes The properties include the formation of zwitter ions and the isoelectric point. Can be assessed for up to three 2-amino acids condensing to form a trimer. Need - Carbohydrates
Carbohydrates
B3 Carbohydrates (3h) Aims Describe the structural features of carbohydrates. Draw the straight-chain and ring structures of glucose and fructose. Describe the condensation of monosaccharides to form disaccharides and polysaccharides List the major functions of carbohydrates in humans. Compare the structural properties of starch and cellulose. State the meaning of the term dietary fibre and the importance of a diet high in dietary fibre. Clarification notes All have the empirical formula CH2O and contain a carbonyl group and at least two -OH groups. Stress - Lipids
Lipids
B4 Lipids (3.5h) Aims A comparison of the three types of lipids found in the body. The difference between high density lipoprotein cholesterol (HDL) and low density lipoprotein (LDL) cholesterol and their importance. Describe the difference in structure between saturated and unsaturated fatty acids. Compare the structures of linoleic (omega-6) and linolenic (omega 3) fatty acids and their importance. Define the term iodine number and use it to calculate the amount of unsaturation in a fat/oil. Describe the condensation reaction of propane-1,2,3-triol (glycerol) with three - Micro- & macro-nutrients
Micro- & macro-nutrients
B5 Micronutrients & macronutrients (2h) Aims Understand the essential difference between micro- and macro-nutrients. Make a comparison between the structures of vitamin A (retinol), vitamin D (calciferol) and vitamin C (ascorbic acid). Deduce from its structure whether a vitamin will be soluble in water or fat. Discuss the causes and effects of nutrient deficiencies and suggests solutions. Clarification notes Micronutrients are required in trace amounts and mainly function as co-enzymes e.g. vitamins and trace minerals (Fe, Cu, F, Zn, I, Se, Mn, Mo, Cr, - Hormones
Hormones
B6 Hormones (3h) Aims Outline the production and function of hormones in the body. Compare the structure of the sex hormones with cholesterol. Describe how oral contraceptives work. Outline the use and abuse of steroids. Clarification notes Hormones are secreted into the blood by the endocrine glands. They are 'chemical messengers'. Examples include: ADH, aldosterone, estrogen, progesterone, testosterone, insulin, epinephrine (adrenaline) and thyroxine. They have a common steroid backbone but vary in their functional groups. Teaching tips: 'Hormones' are a rather varied group of substances in - Enzymes
Enzymes
B7 Enzymes (3h) Aims The characteristics of enzymes need to be described. Make a comparison between enzymes and inorganic catalysts. Describe the relationship between substrate concentration and enzyme activity. Use graphical means to determine Vmax and Km (the Michaelis-Menten constant) and explain their significance. Describe the mechanism of enzyme action. Compare competitive and non-competitive inhibition. State and explain the effects of heavy metal ions, temperature and pH changes on the activity of enzymes. Clarification notes Enzymes are biological catalysts. They are proteins and their - Nucleic acids
Nucleic acids
B8 Nucleic acids (3h) Aims Describe the structure of nucleotides and their condensation polymers - nucleic acids or polynucleotides. Distinguish between the structures of DNA and RNA. Explain the double helix structure of DNA. Describe the role of DNA as the repository of genetic information and explain its role in protein synthesis. Outline the steps in DNA profiling and state its uses. Clarification notes A nucleotide contains a phosphate group, a pentose sugar and one of five organic nitrogenous bases, adenine, cytosine, guanine, thymine and uracil. - Respiration
Respiration
B9 Respiration (1h) Aims Make a comparison between aerobic and anaerobic respiration of glucose in terms of redox and in terms of the energy released. Outline the role of copper ions in electron transport and iron ions in oxygen transport. Clarification notes During aerobic respiration glucose is converted into pyruvate and then into carbon dioxide and water. In the absence of air pyruvate is converted into lactic acid in humans whereas yeast converts it into ethanol and carbon dioxide. The appropriate redox equations should be used. Use cytochromes
- Energy
- Option D
Option D
Introduction I must admit that Option D: Medicines and Drugs is one of my favorite options. It used to be part of the old Applied Chemistry course and was dropped when that course was merged into what was then the 'new' Chemistry course during the big revision of 1996. I updated it and taught 'Medicines and Drugs' as a school based option for five years before it was brought back in again as a full option in the next review of the programme in 2001. Rather like Option B: Human- Pharmaceutical products
Pharmaceutical products
D1 Effects, development and administration of drugs (2h) Aims State the different effects that medicines and drugs have on the body. Outline the stages involved in the research, development and testing of new pharmaceutical products. Describe the different ways in which drugs can be administered. Explain the meaning and importance of the terms therapeutic window, tolerance and side-effects. Clarification notes Include: altering the physical state, altering incoming sensory sensations and altering mood or emotions. Mention should also be made of the body's natural healing processes and the - Antacids
Antacids
D2 Antacids (1h) Aims State with an explanation how excess acidity in the stomach can be treated using different bases. Clarification notes Include magnesium and aluminium compounds and sodium hydrogen carbonate. Equations and their quantitative importance should be stressed. Include the addition of alginates and anti-foaming agents such as dimethicone and their effect. Teaching tips: This is a self-contained topic that does not take long to teach as most of the material has already been covered in the core under Topic 1: Quantitative chemistry and Topic 8: Acids and bases - Analgesics
Analgesics
D3 Analgesics (3h) Aims Describe and explain the different ways in which pain is prevented by analgesics. Describe the use of derivatives of salicylic acid and compare the advantages and disadvantages of the use of aspirin and paracetamol (acetaminophen). Compare the structure of morphine, codeine and heroin (diamorphine - a semi-synthetic opiate). Discuss the advantages and disadvantages of using morphine and its derivatives as strong analgesics. Clarification notes Distinguish between mild analgesics which intercept the pain at source (e.g. by interfering with prostaglandins production) and strong analgesics - Depressants
Depressants
D4 Depressants (3h) Aims Describe the effects of depressants. Discuss the social and physiological effects of the use and abuse of ethanol. Describe and explain the techniques used for the detection of ethanol in the breath, blood and urine. Describe the synergistic effects of ethanol with other drugs. Identify other commonly used depressants and describe their structure. Clarification notes Consider the difference between low doses (little or no effect), moderate doses (sedation, soothing reduction in anxiety), and high doses (induce sleep and even cause death). - Stimulants
Stimulants
D5 Stimulants (2.5h) Aims State the physiological effects of stimulants. Compare amphetamines with adrenaline (epinephrine). Discuss the effects (short- and long-term) of taking nicotine. Describe the effects of caffeine and compare the structure of caffeine with the structure of nicotine. Clarification notes Amphetamines and adrenaline (epinephrine) are both derived from the phenylethylamine structure. Amphetamines are known as sympathomimetic drugs as they mimic the effects of adrenaline(epinephrine). Short-term: Increased heart rate, increase in blood pressure, reduction in urine output, in addition to stimulating effects. Long-term :Increased risk of heart disease, coronary - Antibacterials
Antibacterials
D6 Antibacterials (2h) Aims Outline the history of the development of penicillins. Explain the mechanism of penicillins and discuss the effects of altering the side-chain. Discuss and explain the importance of patients completing a full course of penicillin and the effects of over prescription. Clarification notes This should include the discovery by Fleming and how it was developed by Florey and Chain. There is some good TOK in this story including the importance of serendipity. They interfere with the chemicals that bacteria need to build normal cell - Antivirals
Antivirals
D7 Antivirals (1.5h) Aims Describe how viruses differ from bacteria. Describe the different ways in which antiviral drugs can work. Discuss the difficulties associated with solving the AIDS problem. Clarification notes Viruses are smaller than bacteria. They have a central core of DNA (or RNA) surrounded by a protein coat. As they have no nucleus or cytoplasm they do not feed excrete or grow. They can only replicate inside the host cell using materials form the host cell. They may alter the cells genetic material so viruses - Drug action
Drug action
D8 Drug action (2.5h) Aims Describe the importance of geometrical isomerism in drug action. Discuss the importance of chirality in drug action. Explain the importance of the beta-lactam ring in penicillins. Explain the increased potency of heroin (diamorphine) compared to morphine. Clarification notes cis-platin, Pt(NH3)2Cl2, is the obvious example to use. Relate to TOK as the discovery of this drug is a good example of serendipity. Two enantiomers in a racemic mixture may have very different pharmacological effects. The obvious example here is thalidomide but many - Drug design
Drug design
D9 Drug design (2.5h) Aims Discuss the use of a compound library in drug design. Explain the use of combinatorial and parallel chemistry to synthesise new drugs. Describe how computers are used in drug design. Discuss how the polarity of a molecule can be altered to increase its solubility in an aqueous medium and how this facilitates the distribution of the drug around the body. Describe the use of chiral auxilliaries to form the required enantiomer. Clarification notes Contrast the synthesis of a large number - Mind-altering drugs
Mind-altering drugs
D10 Mind-altering drugs (2h) Aims Describe the effects of taking LSD (lysergic acid diethylamide), mescaline and THC (tetrahydrocannabinol). Discuss and compare the structural similarities and differences between the three drugs LSD, mescaline and psilocybin. Discuss the arguments for and against the legalisation of cannabis Clarification notes Note that all three of these drugs are illegal in virtually every country in the world. Stress the importance of the indole ring in their structures and make student aware of the similarities of all three of these halucinogenic drugs.
- Pharmaceutical products
- Option E
Option E
Introduction Option E: Environmental chemistry is a modern version of the old 'Air and Water' option that was on the Applied Chemistry syllabus. It is obviously an important topic and one that students can relate to. Probably the popular (wrong!) view of chemists is that they are people who cause harm to the environment but in fact much good chemistry has been put into cleaning up the environment. Arguably, the single most important cause of increasing life expectancy during the past one hundred years is the contribution that chemists have- Air pollution
Air pollution
E1 Air pollution (2h) Background What is an air pollutant? On 29 August 2003 George W. Bush overruled the 1998 decision by the Clinton administration and declared that carbon dioxide was not an air pollutant. The logic was that it is a natural component of normal air. This meant that the Clean Air Act could not be used to regulate the output of carbon dioxide from cars. It was significant that one of the first things that the Obama administration did when it came into office was to reverse this decision. - Acid deposition
Acid deposition
E2 Acid deposition (1.5h) Background The term 'acid rain' was first coined by Robert Smith (1817-1884) a Scottish chemist, in a book entitled 'Air and Rain: The Beginnings of a Chemical Climatology' published in 1872. Although the effect of polluting gases from the industrial revolution had been noticed even earlier than that, it was not until the 1960s that it was perceived as a serious problem. In everyday parlance 'acid rain' covers all the forms of acid precipitation but the IB more correctly uses the term acid deposition and distinguishes - Greenhouse effect
Greenhouse effect
E3 Greenhouse effect (1.5h) Background Evidence that carbon dioxide levels in the Earth's atmosphere have been steadily increasing over the past fifty years is indisputable. The carbon dioxide levels have been monitored every month since 1958 at Mauna Loa in Hawaii. The average temperature of the Earth has also increased during this period. Both graphs are from the Earth System Research Laboratory. List of known Greenhouse gases according to the Intergovernmental Panel on Climate Change bromotrifluoromethane - Ozone depletion (1)
Ozone depletion (1)
E4 Ozone depletion (1) (1.5h) Background In 1995 the Nobel Prize for Chemistry was awarded to Paul Crutzen, F. Sherwood Rowland and Mario Molina for their work “in atmospheric chemistry, particularly concerning the formation and decomposition of ozone”. In fact the basic facts concerning the natural formation and depletion of ozone (see equations below in Clarification notes) in the stratosphere were established by Sydney Chapman in 1930. Paul Crutzen showed that oxides of nitrogen remained in the atmosphere for a very long time and suggested that they could cause ozone - Dissolved oxygen in water
Dissolved oxygen in water
E5 Dissolved oxygen in water (1.5h) Background The fact that oxygen dissolves in water is essential for aquatic life. The solubility of oxygen in water depends on several factors with the two most important ones being the salinity of the water and the temperature – an increase in both lowers the amount of dissolved oxygen. The amount of dissolved oxygen present also depends upon the amount of algae or organic material in the water both of which use up oxygen. Biochemical oxygen demand (BOD) is a measure of the amount - Water treatment
Water treatment
E6 Water treatment (2.5h) Background Summary of the sewage treatment process (image from Pakwater Care Services) Aims List the primary pollutants found in waste water and identify their sources. Outline the primary, secondary and tertiary stages of waste water treatment and state the substance that is removed during each stage. Evaluate the process to obtain fresh water from sea-water using multi-stage distillation and reverse osmosis. Clarification notes Examples include: heavy metals, pesticides, dioxins, polychlorinated biphenyls (PCBs), organic matter, nitrates and phosphates. Primary: Cover filtration and sedimentation. - Soil
Soil
E7 Soil (2.5h) Background Salinization is often caused by irrigation with salty water. The photograph from the United States Department of Agriculture shows fields in California suffering from severe salinization. Aims Discuss salinization, nutrient depletion and soil pollution as causes of soil degradation. Describe the relevance of the soil organic matter (SOM) in preventing soil degradation, and outline its physical and biological functions. List common organic soil pollutants and their sources. Clarification notes Salinization: The result of continually irrigating soils. Irrigation water contains dissolved salts, which are - Waste
Waste
E8 Waste (2h) Background Scavenging for waste metal in Freetown, Sierra Leone This topic can be used to good effect for both 'Aim 8' and CAS (Creativity, Action & Service). One of the problems with putting waste into landfill in many developing countries is that children earn a living by working (sometimes actually living) on the sites scavenging and recycling metals and other materials. This hazardous practice violates the human rights of the child. One of the things that students in your school can do is ensure that an efficient method - Ozone depletion (2)
Ozone depletion (2)
E9 Ozone depletion (2) (1h) Background The Antarctic ozone ‘hole’ develops each year between late August and early October. NASA has been measuring Antarctic ozone levels since the early 1970s. Large regions of depleted ozone were first observed over Antarctica in the early 1980s and the size of the ‘hole’ has continued to develop. It is hoped that the size of the holes will soon see a reduction in ozone loss as levels of ozone-depleting chlorofluorocarbons, CFCs, are gradually reduced. Ozone levels are measured using an instrumnet called a Total
- Air pollution
- Option G
Option G
Introduction Option G is probably one of the more intellectual of the seven options. Gone are the days when organic chemistry required a phenomenal memory. It used to be a collection of named reactions (for example, the Wurtz reaction, Diels-Alder rearrangements and Friedel-Crafts reactions) and named reagents (for example, Brady’s reagent, Fehling’s reagent and Tollen’s reagent) but all this has changed. Following on from Gilbert Lewis’s workThe American chemist Gilbert Lewis (1875-1946) is probably the most famous chemist from the past 100 years never to win a Nobel Prize. His work- Electrophilic addition reactions
Electrophilic addition reactions
G1 Electrophilic addition reactions (3h) Background Vladimir Markokovnikov (1838-1904) was a Russian chemist who in 1869, on the basis of little evidence, formulated the rule that when H-X adds to alkenes the hydrogen atom bonds to the carbon atom that already contains the most hydrogen atoms. This is useful for predicting the product but it is not an explanation. The explanation in terms of the stability of the intermediate carbocation was put forward by Morris Kharash (1895-1957) in 1933. Apart from Mendeleyev, Markovnikov is probably the only other Russian chemist - Nucleophilic addition reactions
Nucleophilic addition reactions
G2 Nucleophilic addition reactions (2h) Background Hydrogen cyanide is a weak acid. It can be formed in situ by the addition of hydrogen ions to a solution of cyanide ions, :CN–(aq). The cyanide ion is a good nucleophile and also a good ligand. The reason it is so poisonous is that it acts as a Lewis base by using its non bonding electron pair to form a coordinate bond to the iron in cytochrome c oxidase which interferes with the electron transport chain hindering respiration. Its potential as an insecticide - Elimination reactions
Elimination reactions
G3 Elimination reactions (1h) G4 Addition-elimination reactions (1h) Background information 1. Mechanism for elimation of water from alcohols 2. Structure and model of a molecule of 2,4-dinitrophenylhydrazine Aims Using equations, describe the dehydration reactions of alcohols to form alkenes using phosphoric acid as the dehydrating agent. Explain the mechanism for the elimination of water from alcohols to form alkenes. Using equations, describe the reactions of 2,4-dinitrophenylhydrazine (2,4-DNPH) with aldehydes and ketones. Clarification notes Phosphoric acid is used in preference - Addition-elimination reactions (1)
Addition-elimination reactions (1)
G3 Elimination reactions (1h) G4 Addition-elimination reactions (1) (1h) Background information 1. Mechanism for elimation of water from alcohols 2. Structure and model of a molecule of 2,4-dinitrophenylhydrazine Aims Using equations, describe the dehydration reactions of alcohols to form alkenes using phosphoric acid as the dehydrating agent. Explain the mechanism for the elimination of water from alcohols to form alkenes. Using equations, describe the reactions of 2,4-dinitrophenylhydrazine (2,4-DNPH) with aldehydes and ketones. Clarification notes Phosphoric acid is used in - Arenes
Arenes
G5 Arenes (2.5h) Background The elucidation of the structure of benzene provides an interesting example of how science can progress. The structure of benzene had been puzzling chemists for years as none of the linear structures proposed could explain its properties. Friedrich Kekulé (1829-1896) was originally trained as an architect but switched to studying chemistry after hearing a lecture by Justus von Liebig. Kekulé was one of the originators of the theory of valency and the fact that carbon showed tetravalency. In 1865 he published a paper on the structure - Organometallic chemistry
Organometallic chemistry
G6 Organometallic chemistry (2.5h) Background Although organometallic chemistry is a a large branch of chemistry this small introduction is limited to alkyl magnesium halides, R-Mg-X, collectively known as Grignard reagents. They are named after Victor Grignard (1871-1935) a French professor of Chemistry who won the Nobel prize in 1912 for his discovery. Victor Grignard is less well-known for his work on developing and detecting poison gases such as phosgene, COCl2, and mustard gas, S(CH2CH2Cl)2 during World War 1. The principle use of Grignard reagents is to synthesise a large number of - Reaction pathways
Reaction pathways
G7 Reaction pathways (1h) Background The structure of chlorophyll The American Robert Woodward (1917-1979) who was a Professor at Harvard University was one of the greatest organic chemists of the last century. In 1965 he was awarded the Nobel Prize for Chemistry. Among his great achievements was the synthesis of chlorophyll. This required 55 separate steps. This sub-topic on reaction pathways is not quite so ambitious (it is limited to two steps!) but it is worth pointing out to students the importance of organic synthesis and the general - Acid-base reactions
Acid-base reactions
G8 Acid-base reactions (2h) Background Although only mildly acidic, phenol (pKa≃10) needs to be handled carefully as it is toxic and can cause severe ‘phenolic’ burns. Phenol was first isolated from coal tar in 1834. It has the common name ‘carbolic acid’ and was used as an antiseptic during surgery by Lister in the nineteenth century. Substituted phenols, such as 2,4,6-trinitrophenol (picric acid) are much more acidic. As well as contributing to the acidity the nitro group can also increase the likelihood of explosion and picric acid needs to be - Addition-elimination reactions (2)
Addition-elimination reactions (2)
G9 Addition-elimination reactions (2) (2h) Background Summary of reactions of ethanoyl chloride (Note that the reactions of ethanoic anhydride produce the same organic products but with the formation of ethanoic acid, CH3COOH, rather than HCl. Acid chlorides are more reactive towards nucleophiles than acid anhydrides as chlorine is a better leaving group than -OCOR.) Aims Using equations, describe the reactions of acid anhydrides with nucelophiles to form carboxylic acids, esters, amides and substituted amides. Using equations, describe the reactions of acyl chlorides with nucleophiles to form carboxylic acids, - Electrophilic substitution reactions
Electrophilic substitution reactions
G10 Electrophilic substitution reactions (4h) Background Summary of electrophilic substitution reactions of benzene In all these reactions one of the hydrogen atoms in the benzene ring is substituted by an electrophile. The function of the H2SO4 in nitration and the halogen carrier, AlCl3, in chlorination, alkylation and acylation is to produce the elcectrophile. They do this by accepting a pair of electrons from the reacting species, HNO3, Cl2, RCl and ROCl, i.e. they are functioning as Lewis acids. Aims Using equations, describe the chlorination, nitration, alkylation and acylation reactions of
- Electrophilic addition reactions
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Selected Pages
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Scavenging for waste metal in Freetown, Sierra Leone This topic can be used to good effect for both 'Aim 8' and CAS (Creativity, Action & Service). One of the problems with putting waste... more»
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Option G is probably one of the more intellectual of the seven options. Gone are the days when organic chemistry required a phenomenal memory. It used to be a collection of named... more»
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Summary of the sewage treatment process (image from Pakwater Care Services) List the primary pollutants found in waste water and identify their sources. Outline the primary, secondary and tertiary stages of... more»
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The fact that oxygen dissolves in water is essential for aquatic life. The solubility of oxygen in water depends on several factors with the two most important ones being the salinity of... more»
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The Antarctic ozone ‘hole’ develops each year between late August and early October. NASA has been measuring Antarctic ozone levels since the early 1970s. Large regions of depleted ozone were first observed... more»
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1. (a) Draw the Lewis structures for oxygen, O2(g), and ozone, O3(g). (b) The IB Data Booklet gives 6.63 x 10-34 J s for the value of Planck’s constant and 6.02... more»
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- ► Techniques & principles
- ►▼ Infrared spectroscopy
- ► Mass spectrometry
- ►▼ 1H NMR spectroscopy (1)
- ►▼ Spectroscopy questions
- ► Question 1
- ► Question 2
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- ► Question 4
- ► Question 5
- ► Question 6
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- ► Question 9
- ► Question 10
- ► Atomic absorption
- ►▼ Chromatography (1)
- ►▼ UV-VIS spectroscopy
- ► 1H NMR spectroscopy (2)
- ► Chromatography (2)
- ►▼ Option B
- ►▼ Option D
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