(a)(i) Define the term addition polymerization (ii) What type of organic compounds undergo addition polymerization (iii) List two factors which affect the s...

(a)(i) Addition polymerization. It is the process in which many small unsaturated molecules (monomers containing C=C double bonds) join together to form a single large molecule (the polymer) without the loss of any small molecule.

(a)(ii) Type of compounds that undergo it: unsaturated organic compounds, that is alkenes (and other molecules containing a carbon-to-carbon double bond).

(a)(iii) Two factors affecting the strength of polymers:

• the chain length (relative molecular mass) of the polymer;
• the degree of branching / cross-linking between the chains (and the strength of intermolecular forces between chains).

(b) Reaction pathways of ethanol. Reading the diagram: ethanol (C₂H₅OH) reacts with propanoic acid (CH₃CH₂COOH) and an H⁺ catalyst to give X at the top; step A converts ethanol to CH₃COOH; step B converts ethanol to C₂H₄.

(b)(i) Product X. Ethanol and propanoic acid undergo esterification, so X is ethyl propanoate.

\[ \text{CH}_3\text{CH}_2\text{COOH} + \text{C}_2\text{H}_5\text{OH} \xrightarrow{\text{H}^+} \text{CH}_3\text{CH}_2\text{COOC}_2\text{H}_5 + \text{H}_2\text{O} \]

Structural formula of X: CH₃–CH₂–C(=O)–O–CH₂–CH₃

(b)(ii) Reagent for step A (ethanol \(\rightarrow\) ethanoic acid): acidified potassium dichromate(VI), K₂Cr₂O₇/H⁺ (acidified KMnO₄ is also acceptable), used as an oxidising agent with heat under reflux.

(b)(iii) Type of reaction in step B (ethanol \(\rightarrow\) ethene): a dehydration (elimination) reaction, in which a molecule of water is removed.

\[ \text{C}_2\text{H}_5\text{OH} \xrightarrow[180^{\circ}\text{C}]{\text{conc. H}_2\text{SO}_4} \text{C}_2\text{H}_4 + \text{H}_2\text{O} \]

(c) Complete combustion of ethanol.

\[ \text{C}_2\text{H}_5\text{OH} + 3\text{O}_2 \rightarrow 2\text{CO}_2 + 3\text{H}_2\text{O} \]

From the equation, 1 mole of ethanol requires 3 moles of oxygen. At s.t.p. the volume of oxygen needed to burn one mole of ethanol completely is:

\[ V(\text{O}_2) = 3 \times 22.4 = 67.2\ \text{dm}^3 \]

(For a given mass \(m\) of ethanol, molar mass \(=46\), the volume is \(\dfrac{m}{46}\times 3\times 22.4\ \text{dm}^3\).)

(d)(i) Two substances produced when coal is heated in the absence of air: coke (solid residue) and coal gas; coal tar and ammoniacal liquor are also produced.

(d)(ii) Name of the process: destructive distillation of coal.

(d)(iii) Importance of the non-volatile residue (coke) to the iron and steel industry: coke is used in the blast furnace both as the fuel that supplies heat and as the reducing agent that reduces iron(III) oxide to iron:

\[ \text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2 \]

(the carbon monoxide reducer is itself generated from the burning coke).