Zadanie 5b
Wzorowane na: Chemistry HL Paper 2, November 2023, TZ2, 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 is a low-density metal that is used in lightweight alloys.
Polecenie
Aluminium is produced by the electrolysis of molten aluminium oxide (in industry dissolved in molten cryolite to lower the operating temperature). A simplified cell is shown in the diagram.
(i) Outline why the molten mixture is classified as an electrolyte.
(ii) Identify the electrode at which aluminium is produced and the polarity of that electrode.
(iii) Write a balanced equation for the reaction that occurs at the other electrode.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
(i) it contains mobile / freely moving ions «Al3+ and O2−» «that carry the current» ✔
(ii) Electrode: cathode AND Polarity: negative ✔
(iii) 2 O2− → O2 + 4 e− ✔
OR
✔
OR
C + 2 O2− → CO2 + 4 e− ✔ «carbon anodes»
Schemat punktowania
(i) [1]. (ii) [1]: both the electrode and its polarity are needed. (iii) [1]: a balanced equation with electrons is required; ignore state symbols; do not apply ECF.