2. Atoms, molecules and stoichiometry
A section of Chemistry, 9701
Listing 10 of 208 questions
Use of the Data Booklet is relevant to this question. The combustion of fossil fuels is a major source of increasing atmospheric carbon dioxide, with a consequential rise in global warming. Another significant contribution to carbon dioxide levels comes from the thermal decomposition of limestone, in the manufacture of cement and of lime for agricultural purposes. Cement works roast 1000 million tonnes of limestone per year and a further 200 million tonnes is roasted in kilns to make lime. What is the total annual mass output of carbon dioxide (in million tonnes) from these two processes?
9701_s08_qp_1
MCQ
2008
Paper 1, Variant 0
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Use Recently much interest has been shown in the production of the fuel biodiesel from algae. Up to 55% of the mass of the dried algae is composed of lipids, the majority of which are triglycerides. To convert triglycerides into biodiesel, the following processes are carried out. C17H35CO2CH2 3C17H35CO2H C17H35CO2H C17H35CO2CH2 a triglyceride, Mr = 890 biodiesel, Mr = 298 C17H35CO2CH CH2OH C17H35CO2CH3 CH2OH glycerol CHOH + I II Name the functional group present in triglycerides. Suggest reactants and conditions for reaction I, reaction II. Suggest the structural formula of the compound formed when glycerol is reacted with an excess of HBr, an excess of hot acidified K2Cr2O7. Examiner’s Use Calculate the mass of biodiesel that can be produced from 1000 kg of dried algae, assuming that 50% of the algal mass is triglycerides. mass = kg Construct an equation for the complete combustion of biodiesel. Use your equation to calculate the mass of CO2 produced when 10 kg of biodiesel is burned. The production of biodiesel is at present an expensive process. Suggest a reason why the development of biodiesel as an alternative to fossil fuels is important.
9701_s08_qp_4
THEORY
2008
Paper 4, Variant 0
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Some intercontinental jet airliners use kerosene as fuel. The formula of kerosene may be taken as C14H30. To which homologous series of compounds does kerosene belong? When kerosene burns in an excess of air, carbon dioxide and water form. Balance the following equation for the complete combustion of kerosene. C14H30+ O2CO2+ H2O In this section, give your answers to one decimal place. The flight path from Beijing to Paris is approximately 8195 km. A typical intercontinental jet airliner burns 10.8 kg of kerosene for each kilometre covered. Calculate the mass, in tonnes, of C14H30 burnt on a flight from Beijing to Paris. [1 tonne = 1 000 kg] Use your equation in to calculate the mass, in tonnes, of CO2 produced during this flight. Bicycles may be carried on commercial airliners. When carried on airliners, bicycles are placed in the luggage hold. This is a part of the aircraft which, in flight, will have different temperatures and air pressures from those at sea level. This question concerns the change in pressure in an inflated bicycle tyre from when it is at sea level to when it is in the hold of an airliner in flight. At sea level and a temperature of 20 °C an inflated bicycle tyre contains 710 cm3 of air at an internal pressure of 6 × 105 Pa. Use the general gas equation PV = nRT to calculate the amount, in moles, of air in the tyre at sea level. The same bicycle, with its tyres inflated at sea level as described in above, is placed in the luggage hold of an airliner. At a height of 10 000 m, the temperature in the luggage hold is 5 °C and the air pressure is 2.8 × 104 Pa. Assuming the volume of the tyre does not change, use your answer to to calculate the pressure inside the tyre at a height of 10 000 m.
9701_s11_qp_21
THEORY
2011
Paper 2, Variant 1
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Questions Discovered
208