Zadanie 29
Wzorowane na: Chemistry HL Paper 1, November 2024, pytanie 29. Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
Darmowe konto pozwoli wrócić do niego później.
Polecenie
A voltaic cell is constructed from a half-cell of metal M in a solution of M2+ ions and a half-cell of metal N in a solution of N2+ ions. The half-cells are joined by a salt bridge and an external wire.
M2+(aq) + 2 e− ⇌ M(s) E⊖ = −0.45 V
N2+(aq) + 2 e− ⇌ N(s) E⊖ = +0.30 V
What happens when the cell produces an electric current?
A. The concentration of N2+ ions decreases.
B. Electrons flow from the N half-cell to the M half-cell through the external wire.
C. The mass of the M electrode increases.
D. Negative ions move through the salt bridge towards the N half-cell.
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
A ✔
«the half-cell with the more negative E⊖ is the anode: M is oxidized (M → M2+ + 2 e−) and loses mass, and electrons flow through the wire from M to N; at N the reaction N2+ + 2 e− → N takes place, so [N2+] decreases; negative ions in the salt bridge move towards the anode (the M half-cell)»
Schemat punktowania
One mark for the correct option.