Chemistry 9701/22 — October/November 2011
Cambridge AS Level · AS Level Structured Questions · worked solutions for every part, with the mark scheme
Topics Atoms, Molecules and Stoichiometry · Organic Synthesis · Hydroxy Compounds · States of Matter · Atomic Structure · Chemical Periodicity · +5 more
Compound A is an organic compound which contains carbon, hydrogen and oxygen.
When 0.240 g of the vapour of A is slowly passed over a large quantity of heated copper(II) oxide, CuO, the organic compound A is completely oxidised to carbon dioxide and water. Copper is the only other product of the reaction.
The products are collected and it is found that 0.352 g of and 0.144 g of are formed.
In this section, give your answers to three decimal places.
Calculate the mass of carbon present in 0.352 g of .
Use this value to calculate the amount, in moles, of carbon atoms present in 0.240 g of A.
Calculate the mass of hydrogen present in 0.144 g of .
Use this value to calculate the amount, in moles, of hydrogen atoms present in 0.240 g of A.
Use your answers to calculate the mass of oxygen present in 0.240 g of A.
Use this value to calculate the amount, in moles, of oxygen atoms present in 0.240 g of A.
Use your answers to (a) to calculate the empirical formula of A.
When a 0.148 g sample of A was vapourised at 60 °C, the vapour occupied a volume of 67.7 cm³ at a pressure of 101 kPa.
Use the general gas equation to calculate of A.
= ......................
Hence calculate the molecular formula of A.
Compound A is a liquid which does not react with 2,4-dinitrophenylhydrazine reagent or with aqueous bromine.
Suggest two structural formulae for A.
Compound A contains only carbon, hydrogen and oxygen.
Explain how the information on the opposite page about the reaction of A with CuO confirms this statement.
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