Answers to questions on condensation polymers

1. (a) Polyester

(b)

(c) n HOOC−C₆H₄−COOH + n HO−CH₂−CH₂−CH₂−OH → H−(−O−(CH₂)₃−OCO−C₆H₄−CO−)_n−OH + (2n−1) H₂O

(d) M_r (HOOC−C₆H₄−COOH) = (8 x 12.01) + (6 x 1.01) + (4 x 16.00) = 166.14
M_r (HO−CH₂−CH₂−CH₂−OH) = (3 x 12.01) + (8 x 1.01) + (2 x 16.00) = 76.11
Total mass of 1000 mol of reactants = 166.14 + 76.11 = 242.25 kg
Total mass of water formed = 1999 x 18.02/1000 = 36.02 kg
Mass of polymer = 242.25 − 36.02 = 206.23 kg
Atom economy = (206.23 ÷ 242.25) x 100 = 85.1 %

2. (a) Polyamide.

(b)

(c) The long polymer chains are able to form a strong 3-dimensional cross linkage to make strong layers due to hydrogen bond formation between the H bonded to the N atom in one peptide linkage with the O of an adjacent peptide linkage.

(d) The acid protonates the O and N atoms in the peptide bonds so they can no longer form hydrogen bond cross linkages. The concentrated acid may also hydrolyse the peptide bond.

Answers to Condensation polymers questions