Q25 · CSIR NET Chemistry, December 2016
Paper: CSIR NET December 2016 · Subject: Physical Chemistry · Chapter: Chemical Kinetics · Topic: Arrhenius Activation · Marks: 2 · Difficulty: Medium
For two reactions
\[ \begin{array}{ll} \mathrm{X(g)+Y(g) \rightarrow Z(g)} & (1) \\ \mathrm{M(g)+N(g) \rightarrow P(g)} & (2) \end{array} \]
according to the collision theory, the ratio of squares of pre-exponential factors of reactions 2 ($A_2$) and 1 ($A_1$) at the same temperature, $\left(\dfrac{A_2}{A_1}\right)^{2}$ | Species | Mass (g/mol) | Diameter (nm) |
|---|---|---|
| X | 5 | 0.3 |
| Y | 20 | 0.5 |
| M | 10 | 0.4 |
| N | 10 | 0.4 |
(a)4/5
(b)5/5
(c)$5 / 3$
(d)3/5
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
A ∝ σ√(8kT/πμ). Both collision diameters are (0.3 + 0.5)/2 = 0.4 nm and 0.4 nm, so σ is equal. μ₁ = 5 × 20/25 = 4 and μ₂ = 10 × 10/20 = 5, so (A₂/A₁)² = μ₁/μ₂ = 4/5 (a).
Study loop for Chemical Kinetics