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For the reaction 3A + 2B + C → products, the following initial-rate data were obtained at different starting concentrations:
Initial rate (M s⁻¹) | [A]0 (M) | [B]0 (M) | [C]0 (M)
5.0 × 10⁻³ | 0.010 | 0.005 | 0.010
5.0 × 10⁻³ | 0.010 | 0.005 | 0.015
1.0 × 10⁻² | 0.010 | 0.010 | 0.010
1.25 × 10⁻³ | 0.005 | 0.005 | 0.010
The reaction orders with respect to A, B and C, in that order, are:
- 3, 2, 0
- 3, 2, 1
- 2, 2, 0
- 2, 1, 0
Correct answer: 2, 1, 0
Solution
Rows 1->2: C changes, rate same -> order C=0. Rows 1->3: B doubled, rate doubled -> order B=1. Rows 1->4: A halved, rate quartered -> order A=2. So orders are 2, 1, 0.
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