HL Paper 3
Describe the function of chlorophyll in photosynthesis.
Compare and contrast the structures of starch and cellulose.
One similarity:
One difference:
Explain why maltose, C12H22O11, is soluble in water.
Polymer nanocomposites often have better structural performance than conventional materials. Lithographic etching and metal coordination are two methods of assembling these nanocomposites.
Dendrimers are highly branched nanoparticles with a wide range of usage. One such dendrimer is PAMAM, or polyamidoamine.
The first step in the synthesis is to make the core by reacting ethane-1,2-diamine with methylpropenoate.
Estimate the atom economy of this first step.
Suggest, giving one reason, whether this is an addition or condensation reaction.
Subsequent steps proceed under differing conditions, forming the dendrimer polymer with the following repeating unit.
State the name of one functional group in this repeating unit.
Aspartame is formed from the two amino acids aspartic acid (Asp) and phenylalanine (Phe).
Chromatography is used in the analysis of proteins in the food and pharmaceutical industry.
Draw the structure of the dipeptide Asp–Phe using section 33 of the data booklet.
Describe, using another method, how a mixture of four amino acids, alanine, arginine, glutamic acid and glycine, could be separated when placed in a buffer solution of pH 6.0.
Suggest why alanine and glycine separate slightly at pH 6.5.
Calculate the ratio of [A−] : [HA] in a buffer of pH 6.0 given that pKa for the acid is 4.83, using section 1 of the data booklet.
Changes in physiology can impact living creatures.
The graph shows the change in oxygen partial pressure in blood, measured at different pH values.
Explain the effect of changing pH on the percentage saturation of hemoglobin at a given partial pressure of oxygen.
Explain the biomagnification of the pesticide DDT.
Vitamins are organic compounds essential in small amounts.
State the name of one functional group common to all three vitamins shown in section 35 of the data booklet.
Gasoline (petrol), biodiesel and ethanol are fuels.
[U.S. Department of Energy. https://afdc.energy.gov/]
Calculate the energy released, in , from the complete combustion of of ethanol.
State a class of organic compounds found in gasoline.
Outline the advantages and disadvantages of using biodiesel instead of gasoline as fuel for a car. Exclude any discussion of cost.
A mixture of gasoline and ethanol is often used as a fuel. Suggest an advantage of such a mixture over the use of pure gasoline. Exclude any discussion of cost.
When combusted, all three fuels can release carbon dioxide, a greenhouse gas, as well as particulates. Contrast how carbon dioxide and particulates interact with sunlight.
Methane is another greenhouse gas. Contrast the reasons why methane and carbon dioxide are considered significant greenhouse gases.
Suggest a wavenumber absorbed by methane gas.
Determine the relative rate of effusion of methane () to carbon dioxide (), under the same conditions of temperature and pressure. Use section 1 of the data booklet.
Stearic acid (Mr = 284.47) and oleic acid (Mr = 282.46) have the same number of carbon atoms. The structures of both lipids are shown in section 34 of the data booklet.
The iodine number is the number of grams of iodine which reacts with 100 g of fat. Calculate the iodine number of oleic acid.
The chemical change in stored fats causes rancidity characterized by an unpleasant smell or taste.
Compare hydrolytic and oxidative rancidity.
State one similarity and one difference in composition between phospholipids and triglycerides.
Similarity:
Difference:
Kevlar® is used to make racing tires.
Draw the structure of the monomers of Kevlar® if the by-product of the condensation polymerization is hydrogen chloride.
State and explain why plasticizers are added to polymers.
Discuss why the recycling of plastics is an energy intensive process.
Steroids are lipids with a steroidal backbone. The structure of cholesterol is shown in section 34 of the data booklet.
Infrared (IR) spectroscopy is used to identify functional groups in organic compounds.
Deduce the wavenumber, in cm−1, of an absorption peak found in the IR spectrum of testosterone but not in that of cholesterol.
Describe a technique for the detection of steroids in blood and urine.
Explain how redox chemistry is used to measure the ethanol concentration in a breathalyser.
Antimony oxide is widely used as a homogeneous catalyst for the reaction of benzene-1,4-dicarboxylic acid with ethane-1,2-diol in the production of polyethylene terephthalate (PETE).
Deduce the repeating unit of the polymer and the other product of the reaction.
State the class of polymer to which PETE belongs.
Aspirin is one of the most widely used drugs in the world.
Aspirin was synthesized from 2.65 g of salicylic acid (2-hydroxybenzoic acid) (Mr = 138.13) and 2.51 g of ethanoic anhydride (Mr = 102.10).
Suggest two absorbances, other than the absorbances due to the ring structure and C–H bonds, that would be present in the infrared (IR) spectrum of aspirin.
State two techniques, other than IR spectroscopy, which could be used to confirm the identity of aspirin.