Zadanie 5b
Wzorowane na: Chemistry HL Paper 2, November 2023, TZ1, pytanie 5(b). Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Informacja do zadań 5a-5h.
Aluminium has a low density, which is why it is widely used in aircraft and in specialized alloys.
Polecenie
Aluminium is produced industrially by the electrolysis of aluminium oxide dissolved in molten cryolite, as shown in the diagram.
(i) Outline why the molten mixture is considered to be an electrolyte.
(ii) Identify the electrode at which aluminium forms and state its polarity.
(iii) Write a balanced equation for the reaction at the electrode that you did not identify in (ii).
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) «contains» ions «Al3+ and O2−» that are free to move ✔
(ii) Electrode: cathode AND Polarity: negative ✔
(iii) 2 O2− → O2 + 4 e− ✔
OR
✔
Schemat punktowania
(i) [1]. Accept a statement that the ions can carry the current. (ii) [1] for both the electrode and the polarity. (iii) [1]; accept e for e⁻ and ignore state symbols. Do not apply ECF. Ignore any reaction of the oxygen with the carbon anode.