IB DP Chemistry D.3 Opiates HL Paper 3

Question

Explain how strong analgesics like morphine work.

Answer/Explanation

Answer:

«temporarily» binding to receptors in the nervous system/spinal cord/brain

preventing transmission of pain impulses

Question

Drugs are commonly prescribed by medical professionals to treat illness.

(a) State two different drug administration methods.

(b) Explain how aspirin works as a mild analgesic.

(c) Deduce the structural formulae of the missing reactant A and product B in the synthesis of aspirin from salicylic acid.

(d) State one advantage and one disadvantage of prescribing opiates to patients.

Advantage:
Disadvantage:

Answer/Explanation

Answer:

(a) Any two of:
oral
inhalation
topical/applied to the skin
parenteral/injection
suppositories
eye/ear drops

(b) interferes with pain at source «of injury»
prevents release of prostaglandins/substances causing swelling/pain

(c) ALTERNATIVE 1:
A: \(CH_3COOCOCH_3\)
B: \(CH_3COOH\)
ALTERNATIVE 2:
A: \(CH_3COOH\)
B: \(H_2O\)
ALTERNATIVE 3:
A: \(CH_3COCl\)
B: HCl

(d) Advantage:
strong/severe/surgical pain relief
OR
stops coughing reflex
OR
fast action
Disadvantage:
addiction
OR
constipation
OR
tolerance «leading to overdose»

Question

Drugs are commonly prescribed by medical professionals to treat illness.

(a) State two different drug administration methods.

(b) Explain how aspirin works as a mild analgesic.

(c) Deduce the structural formulae of the missing reactant A and product B in the synthesis of aspirin from salicylic acid.

(d) State one advantage and one disadvantage of prescribing opiates to patients.

Advantage:
Disadvantage:

Answer/Explanation

Answer:

(a) Any two of:
oral
inhalation
topical/applied to the skin
parenteral/injection
suppositories
eye/ear drops

(b) interferes with pain at source «of injury»
prevents release of prostaglandins/substances causing swelling/pain

(c) ALTERNATIVE 1:
A: \(CH_3COOCOCH_3\)
B: \(CH_3COOH\)
ALTERNATIVE 2:
A: \(CH_3COOH\)
B: \(H_2O\)
ALTERNATIVE 3:
A: \(CH_3COCl\)
B: HCl

(d) Advantage:
strong/severe/surgical pain relief
OR
stops coughing reflex
OR
fast action
Disadvantage:
addiction
OR
constipation
OR
tolerance «leading to overdose»

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