Zadanie 2d
Wzorowane na: Chemistry SL Paper 2, May 2023, TZ1, pytanie 2(d). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
Sulfur trioxide is manufactured industrially by the oxidation of sulfur dioxide.
2 SO2(g) + O2(g) ⇌ 2 SO3(g) ΔH⊖ = −198.0 kJ mol−1
(i) Outline what is meant by dynamic equilibrium.
(ii) Deduce the Kc expression for this reaction.
(iii) The oxidation of sulfur dioxide in industry requires a catalyst. State how a catalyst increases the rate of this reaction.
(iv) Sketch a Maxwell-Boltzmann distribution curve showing the activation energies with and without a catalyst.
(v) Suggest how the progress of the reaction could be monitored.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) «in a closed system» the rate of the forward reaction equals the rate of the reverse reaction ✔
(ii) ✔
(iii) provides an alternative reaction pathway with a lower activation energy ✔
(iv) correct shape of curve: starts at the origin, rises to a single peak and falls with a long tail that does not touch the x-axis at high energy ✔
Ea(catalysed) marked on the x-axis at a lower energy than Ea(uncatalysed) ✔
(v) measure the change in pressure / volume «the amount of gas falls from 3 mol to 2 mol»
OR temperature
OR concentration of SO2 / O2 / SO3 ✔
Schemat punktowania
(i) [1]. (ii) [1]: square brackets required. (iii) [1]: both 'alternative pathway' and 'lower activation energy' are needed. (iv) [2]: M1 curve shape, M2 two activation energies marked with the catalysed one lower; ignore any shading under the curve. (v) [1]: accept any valid method that follows a quantity changing during the reaction; do not accept pH.