Zadanie 3c
Wzorowane na: Chemistry SL Paper 2, May 2024, TZ2, pytanie 3(c). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 3a-3d.
Metal oxides and non-metal oxides behave differently when they dissolve in water, and several of them affect the environment.
Polecenie
Hydrogen fluoride, HF, released by aluminium smelters, dissolves in water to form a weak acid.
HF(aq) + H2O(l) ⇌ H3O+(aq) + F−(aq)
(i) State the equilibrium constant expression, Kc, for this reaction.
(ii) State, with a reason, the effect of an increase in temperature on the position of this equilibrium, given that the forward reaction is exothermic (ΔH⊖ < 0).
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) ✔
(ii) the position shifts to the left «towards HF and water» AND the forward reaction is exothermic, so the reverse reaction, which absorbs the added heat, is favoured ✔
Schemat punktowania
(i) [1]: square brackets for concentrations; do not accept an expression that includes liquid water. (ii) [1]: both the direction (to the left) and the reason are needed; accept "the system opposes the rise in temperature by favouring the endothermic reaction".