Zadanie 30
Wzorowane na: Chemistry HL Paper 1, November 2022, pytanie 30. Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
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Polecenie
Some standard electrode potentials for copper are shown.
Cu2+(aq) + e− ⇌ Cu+(aq), E⊖ = +0.15 V
Cu+(aq) + e− ⇌ Cu(s), E⊖ = +0.52 V
Cu2+(aq) + 2 e− ⇌ Cu(s), E⊖ = +0.34 V
Which statement is correct under standard conditions?
A. Cu+(aq) is stable and does not react
B. Cu(s) reacts spontaneously with Cu2+(aq) to form Cu+(aq)
C. Cu+(aq) can act as an oxidizing agent but not as a reducing agent
D. Cu+(aq) reacts spontaneously to form Cu(s) and Cu2+(aq)
Sprawdź rozwiązanieUkryj rozwiązanieKlucz i punktacja
Odpowiedź z klucza
D ✔
«Cu+ is reduced to Cu (+0.52 V) while another Cu+ is oxidized to Cu2+ (+0.15 V): Ecell⊖ = 0.52 − 0.15 = +0.37 V, positive, so 2 Cu+ → Cu + Cu2+ is spontaneous (disproportionation). The reaction of Cu with Cu2+ would have Ecell⊖ = 0.15 − 0.52 = −0.37 V»
Schemat punktowania
One mark for the correct option.