(a) What is meant by each of the following terms?: (i) Esterification (ii) Saponification (b)(i) Give the general moluecular 1 formula of alkynes (ii) Write...

(a)

(i) Esterification is the reaction between an alkanol and an alkanoic acid, in the presence of a mineral acid catalyst such as concentrated sulphuric acid, to form an ester and water.

(ii) Saponification is the alkaline hydrolysis of a fat, oil or ester with an alkali such as sodium hydroxide to produce soap, which is the sodium salt of a fatty acid, and glycerol in the case of fats and oils.

(b)

(i) The general molecular formula of alkynes is: \[\mathrm{C_nH_{2n-2}}\]

(ii) Ethyl ethanoate has molecular formula \(\mathrm{C_4H_8O_2}\). Its empirical formula is \(\mathrm{C_2H_4O}\).

(iii) The displayed structure of 1,1,2,2-tetrabromoethane is:

(iv)

\[2\mathrm{C_2H_5OH}+2\mathrm{Na}\rightarrow2\mathrm{C_2H_5ONa}+\mathrm{H_2}\]

(c)

(i)

1. Fractional distillation.
2. Cracking, usually catalytic cracking.
3. Addition reaction, specifically chlorination of ethene.
4. Addition polymerisation.

(ii) \(X\) is ethene, \(\mathrm{C_2H_4}\), and \(Y\) is chlorine, \(\mathrm{Cl_2}\).

(iii) The IUPAC name of the product in stage III is 1,2-dichloroethane.

\[\mathrm{CH_2{=}CH_2}+\mathrm{Cl_2}\rightarrow\mathrm{ClCH_2CH_2Cl}\]

(iv) Ethene is polymerised at a high temperature of about \(150\text{ to }300^\circ\mathrm{C}\) and high pressure of about \(500\text{ to }1500\) atmospheres, using a trace of oxygen or an organic peroxide as initiator.

(d)

(i) Palm wine froths because yeast ferments the sugars present to ethanol and carbon dioxide. The bubbles of carbon dioxide cause the foaming.

\[\mathrm{C_6H_{12}O_6}\xrightarrow{\text{yeast}}2\mathrm{C_2H_5OH}+2\mathrm{CO_2}\]

(ii) After some days, bacteria oxidise the ethanol in palm wine, in the presence of atmospheric oxygen, to ethanoic acid. Ethanoic acid gives the wine its sour taste.

\[\mathrm{C_2H_5OH}+\mathrm{O_2}\xrightarrow{\text{bacteria}}\mathrm{CH_3COOH}+\mathrm{H_2O}\]