Chemistry 5070 · O Level · Polymers

Polymers — practice question

The structure of glycolic acid is illustrated in the diagram.
(a)[2]

Glycolic acid is a solid at room temperature. Describe the molecular arrangement and motion in glycolic acid at room temperature.

(b(i))[1]

Glycolic acid can polymerise with itself to make a polyester called poly(glycolic acid). What sort of polymer is a polyester?

(b(ii))[2]

Draw a section of the poly(glycolic acid) chain showing at least two repeating units.

(c(i))[3]

Glycolic acid is made by heating methanal, carbon monoxide and water in the presence of a sulfuric acid catalyst. $\text{CH}_2\text{O} + \text{CO} + \text{H}_2\text{O} \rightarrow \text{CH}_2(\text{OH})\text{COOH}$ A 1800 g sample of methanal reacts with excess carbon monoxide and water. The percentage yield of glycolic acid is 45%. Calculate the mass, in grams, of glycolic acid obtained.

(c(ii))[2]

Glycolic acid is a weak acid. Sulfuric acid is a strong acid. Explain how a strong acid differs from a weak acid.

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