DP Chemistry (last assessment 2024)

Test builder »

Question 18M.3.sl.TZ2.16

Select a Test
Date May 2018 Marks available [Maximum mark: 6] Reference code 18M.3.sl.TZ2.16
Level sl Paper 3 Time zone TZ2
Command term Describe, Explain, State Question number 16 Adapted from N/A
16.
[Maximum mark: 6]
18M.3.sl.TZ2.16

Penicillins and aspirin are important medicines.

(a.i)

Describe how penicillin combats bacterial infections.

[2]

Markscheme

«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]

(a.ii)

State how penicillins may be modified to increase their effectiveness.

[1]

Markscheme

modify side chain

[1 mark]

(b)

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

[1]

Markscheme

condensation

OR

esterification

OR

nucleophilic substitution/nucleophilic displacement/SN2

 

Do not accept just “substitution/displacement”.

[1 mark]

(c)

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

[2]

Markscheme

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]

Syllabus sections