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 | 8.00×10−28.00 \times 10^{-2}8.00×10−2 | 2.00×10−22.00 \times 10^{-2}2.00×10−2 |
| 20.0 | 7.20×10−27.20 \times 10^{-2}7.20×10−2 | not measured | |
| 2 | 0 | 16.00×10−216.00 \times 10^{-2}16.00×10−2 | 2.00×10−22.00 \times 10^{-2}2.00×10−2 |
| 20.0 | 12.80×10−212.80 \times 10^{-2}12.80×10−2 | not measured | |
| 3 | 0 | 4.00×10−24.00 \times 10^{-2}4.00×10−2 | 4.00×10−24.00 \times 10^{-2}4.00×10−2 |
| 20.0 | 3.60×10−23.60 \times 10^{-2}3.60×10−2 | 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 | 4.0×10−44.0 \times 10^{-4}4.0×10−4 |
| 2 | |
| 3 |
Determine the order of reaction with respect to P and the order of reaction with respect to Q.
A reaction between substances D and E was first order with respect to D and second order with respect to E. At a given temperature, the initial rate of reaction was 1.25×10−3 mol dm−3 s−11.25 \times 10^{-3}\text{ mol dm}^{-3}\text{ s}^{-1}1.25×10−3 mol dm−3 s−1 when the initial concentration of D was 8.00×10−3 mol dm−38.00 \times 10^{-3}\text{ mol dm}^{-3}8.00×10−3 mol dm−3 and the initial concentration of E was 2.50×10−2 mol dm−32.50 \times 10^{-2}\text{ mol dm}^{-3}2.50×10−2 mol dm−3.
Calculate a value for the rate constant, kkk, for the reaction at this temperature. Give the units for kkk.
