Substances P and Q react in solution at a constant temperature. The initial rate of reaction was studied in three experiments by measuring the change in concentration of P over the first twenty seconds of the reaction. The data obtained are shown in Table 1.
| Experiment | Time after mixing / s\text{s}s | Concentration of P / mol dm−3\text{mol dm}^{-3}mol dm−3 | Concentration of Q / mol dm−3\text{mol dm}^{-3}mol dm−3 |
|---|---|---|---|
| 1 | 0 | 3.00×10−23.00 \times 10^{-2}3.00×10−2 | 2.00×10−22.00 \times 10^{-2}2.00×10−2 |
| 20.0 | 2.76×10−22.76 \times 10^{-2}2.76×10−2 | not measured | |
| 2 | 0 | 6.00×10−26.00 \times 10^{-2}6.00×10−2 | 2.00×10−22.00 \times 10^{-2}2.00×10−2 |
| 20.0 | 5.04×10−25.04 \times 10^{-2}5.04×10−2 | not measured | |
| 3 | 0 | 3.00×10−23.00 \times 10^{-2}3.00×10−2 | 4.00×10−24.00 \times 10^{-2}4.00×10−2 |
| 20.0 | 2.52×10−22.52 \times 10^{-2}2.52×10−2 | not measured |
Calculate the initial rate of reaction of P in experiments 2 and 3 to complete Table 2 below.
| Experiment | Initial rate of reaction of P / mol dm−3 s−1\text{mol dm}^{-3}\text{ s}^{-1}mol dm−3 s−1 |
|---|---|
| 1 | 1.2×10−41.2 \times 10^{-4}1.2×10−4 |
| 2 | |
| 3 |
Determine the order of reaction with respect to P and the order of reaction with respect to Q.
A reaction between substances W and X was first order with respect to W and second order with respect to X. At a given temperature, the initial rate of reaction was 2.16×10−4 mol dm−3 s−12.16 \times 10^{-4}\text{ mol dm}^{-3}\text{ s}^{-1}2.16×10−4 mol dm−3 s−1 when the initial concentration of W was 3.00×10−2 mol dm−33.00 \times 10^{-2}\text{ mol dm}^{-3}3.00×10−2 mol dm−3 and the initial concentration of X was 1.20×10−2 mol dm−31.20 \times 10^{-2}\text{ mol dm}^{-3}1.20×10−2 mol dm−3.
Calculate a value for the rate constant, kkk, for the reaction at this temperature. Give the units for kkk.
