Q4(c)(ii). Yield of P₁ from three parallel paths
In acidic condition, benzyl penicillin (BP) undergoes three parallel reactions: BP → P₁ (k₁), BP → P₂ (k₂) and BP → P₃ (k₃). Imagine while swallowing penicillin, the pH of the stomach is ~3. At this pH and a temperature of 22 °C, the rate constants are k₁ = 7.0 × 10⁻⁴ s⁻¹, k₂ = 4.1 × 10⁻³ s⁻¹, k₃ = 5.7 × 10⁻³ s⁻¹. What is the yield of P₁ formation?
Answer in brief
Yield of P₁ = k₁/(k₁ + k₂ + k₃) = 0.067 = 6.7 %.
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Coversparallel reactionsbranching ratiobenzyl penicillinfirst-order kineticsproduct yield
All parts of Question 4
- 4(a) Triple point, stable phase and enthalpy of sublimation of a new drug15 marks
- 4(b)(i) Polarography and concentration polarisation15 marks
- 4(b)(ii) Concentration cells; fuel cells as energy converters5 marks
- 4(c)(i) Time of maximum concentration of B in A → B → C10 marks
- 4(c)(ii) Yield of P₁ from three parallel paths5 marks