Zadanie 9a
Wzorowane na: Chemistry HL Paper 2, May 2023, TZ2, pytanie 9(a). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 9a-9b.
Rate equations are determined experimentally, and the effect of temperature on the rate constant gives the activation energy.
Polecenie
The initial rate of the iodination of propanone in aqueous acid was measured at constant temperature.
CH3COCH3(aq) + I2(aq) → CH3COCH2I(aq) + HI(aq)
Four experiments were carried out and the results are given in the table.
| Experiment | [CH3COCH3] / mol dm−3 | [I2] / mol dm−3 | [H+] / mol dm−3 | Initial rate / mol dm−3 s−1 |
|---|---|---|---|---|
| 1 | 0.400 | 0.0050 | 0.200 | 2.24 × 10−6 |
| 2 | 0.400 | 0.0100 | 0.200 | 2.26 × 10−6 |
| 3 | 0.800 | 0.0050 | 0.200 | 4.47 × 10−6 |
| 4 | 0.400 | 0.0050 | 0.400 | 4.49 × 10−6 |
Deduce the overall rate equation.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
[CH3COCH3]: first order AND [I2]: zero order AND [H+]: first order ✔
«rate =» k[CH3COCH3][H+] ✔
Schemat punktowania
M1: all three orders correct (experiments 1 and 2 give I2, 1 and 3 give propanone, 1 and 4 give H+); M2: the rate equation, with no I2 term. Award [2] for the correct rate equation. The rate equation cannot be written from the stoichiometry of the equation.