ORGANIC CHEMISTRY

1. Alcohols are a homologous series of organic compounds.

The table shows some information about the first five alcohols.

(a) Suggest the name of the alcohol with the molecular formula C₃H₈O.
(b) Draw the structure of an alcohol with the molecular formula C₄H₁₀O and explain why this alcohol is saturated.
(c) Deduce the molecular formula of an alcohol that contains seven carbon atoms.
(d) Ethanol reacts with ethanoic acid to form ethyl ethanoate.
(i) Draw the structure of ethyl ethanoate.
(ii) Suggest a use for ethyl ethanoate.
(e) Describe, with the aid of an equation, how ethanol is manufactured by fermentation.
(f) When ethanol is heated with concentrated sulfuric acid a colourless gas, A, is produced. Gas A will decolourise aqueous bromine. Identify gas A.

2. Alkanes are a homologous series of saturated hydrocarbons.
(a) What is the general formula of alkanes?
(b) Draw the structures of the two isomers of C₄H₁₀.
(c) One of the isomers of C₄H₁₀, butane, reacts with chlorine in the presence of ultra-violet light. It forms hydrogen chloride gas and a mixture of liquid compounds.
(i) Name this type of reaction.
(ii) Draw the structure of one of the liquid compounds.
(d) Name the process by which butane is separated from crude oil.

3. Propanoic acid, C₂H₅CO₂H, and hydrochloric acid, HCl, both act as acids when dissolved in water.
(a) State the formula of an ion found in both dilute propanoic acid and in dilute hydrochloric acid.
(b) Propanoic acid reacts with magnesium carbonate to form water, a colourless gas and a salt. In this reaction
(i) name the gas,
(ii) give the formula of the salt.
(c) In an experiment magnesium ribbon is added to 25.0 cm³ of 1.00 mol/dm³ hydrochloric acid, an excess.

Mg(s) + 2HCl(aq)  → MgCl₂(aq) + H₂(g)

Every 30 seconds the total volume of hydrogen formed is measured at room temperature and pressure. The results are shown on the grid below.

(i) Use information from the graph to calculate the mass of magnesium ribbon used in the experiment. [One mole of any gas at room temperature and pressure occupies a volume of 24 000 cm³.]
mass of magnesium ribbon = ................................... g [3]

(ii) The experiment was repeated using the same mass of magnesium ribbon but with 25.0 cm3 of 1.00 mol/dm³ propanoic acid, an excess.

Draw on the grid a graph of the results for the reaction between magnesium ribbon and propanoic acid.

(d) Dilute hydrochloric acid reacts with aqueous silver nitrate to form a white precipitate.

Write an ionic equation, with state symbols, for this reaction.