AQA Jun 2010 Paper 2 Q4

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do not write outside the box a scientist used mass spectrometry to analyse a sample of the air near a fertiliser factory the sample of air included traces of a gas which was shown by its molecular ion to have a precise mr a state the meaning of the term molecular ion mark b i use the following data to show that the trace gas was dinitrogen oxide n o show your working atom precise relative atomic mass c n o mark b ii propane is used as a fuel in the fertiliser factory state why both propane and its combustion product carbon dioxide might have been identified as the trace gas if the scientist had used relative molecular masses calculated to one decimal place mark b iii state why the precise relative atomic mass for the c isotope is exactly mark wmp jun chem do not write outside the box c dinitrogen oxide is formed when ammonia is oxidised according to the following equation nh g o g n o g h o l c i use the standard enthalpies of formation in the table below to calculate a value for the standard enthalpy change of this reaction hf kj mol nh g o g n o g h o l marks extra space c ii state one condition necessary for enthalpies of formation to be quoted as standard values at a specified temperature of k mark turn over for the next question turn over wmp jun chem

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