Describe how penicillin combats bacterial infections.

State how penicillins may be modified to increase their effectiveness.

State the type of reaction used to synthesize aspirin from salicylic acid.

Explain why aspirin is not stored in a hot, humid location.

«irreversibly» binds/bonds to enzyme/transpeptidase

OR

inhibits enzyme/transpeptidase «in bacteria» that produces cell walls

OR

prevents cross-linking of bacterial cell walls

cells absorb water AND burst

OR

cells cannot reproduce

[2 marks]

modify side chain

[1 mark]

condensation

OR

esterification

OR

nucleophilic substitution/nucleophilic displacement/S_N2

Do not accept just “substitution/displacement”.

[1 mark]

water causes hydrolysis

OR

aspirin reacts with water

heat increases the rate of hydrolysis

OR

heat increases the rate of the reaction with water

Accept “aspirin will convert into salicylic/ethanoic acid”.

Do not accept “aspirin dissolves in water” OR “aspirin absorbs water/is hygroscopic”.

[2 marks]