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Questions
Consider the following data for the reaction:
\[\ce{A + B -> Product}\]
| Experiment Number | [A] mol L−1 | [B] mol L−1 | Rate mol sec−1 |
| 1. | 0.10 M | 1.0 | 2.1 × 10−3 |
| 2. | 0.20 M | 2.0 | 8.4 × 10−3 |
| 3. | 0.30 M | 3.0 | 8.4 × 10−3 |
Determine the order of reaction with respect to A and with respect to B and the overall order of a reaction.
Consider the following data for the reaction, \[\ce{A + B -> Products}\];
| Run | Initial conc. A | Initial conc. B | Initial rate (mol s−1) |
| 1 | 0.10 M | 1.0 M | 2.1 × 10−3 |
| 2 | 0.20 M | 2.0 M | 8.4 × 10−3 |
| 3 | 0.30 M | 3.0 M | 8.4 × 10−3 |
Determine the order of reaction with respect to A and with respect to B and the overall order of a reaction.
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Solution
The rate law may be expressed as
Rate = k[A]p [B]q
Comparing experiments 2 and 3
(Rate)2 = k[0.2]p [1.0]q = 8.4 × 10−3 ...(i)
(Rate)3 = k[0.2]p [2.0]q = 8.4 × 10−3 ...(ii)
Dividing eqn. by (ii) by (i),
`(("Rate")_3)/(("Rate")_2) = (k[0.2]^p [2.0]^q)/(k[0.2]^p [1.0]^q) = (8.4 xx 10^-3)/(8.4 xx 10^-3)`
[2]q = [2]0 or q = 0
Comparing experiments (i) and (ii)
(Rate)2 = k[0.20]p [1.0]q = 8.4 × 10−3 ...(iii)
(Rate)1 = k[0.10]p [1.0]q = 2.1 × 10−3 ...(iv)
Dividing eqn. (iii) by (iv),
`(("Rate")_2)/(("rate")_1) = (k[0.20]^p [1.0]^q)/(k[0.10]^p [1.0]^q) = (8.4 xx 10^-3)/(2.7 xx 10^-3) = 4`
[2]q = [2]2 or q = 2
order with respect to A = 2
order with respect to B = 0
overall order of reaction = 2
