Question

Consider the redox reaction below.

2 upper A l (s) plus 6 upper H C l (a q) right arrow 2 upper Al upper C l subscript 3 (a q) plus 3 upper H subscript 2 (g).

Which statement correctly describes a half-reaction that is taking place?
Hydrogen is oxidized from +1 to 0.
Chlorine is reduced from –1 to 0.
Aluminum is oxidized from 0 to +3.
Hydrogen is reduced from 0 to –1.

Answer 1

Aluminum is oxidized from 0 to +3.

Explanation: Al(s) → Al3+ + 3 e− (oxidation). Hydrogen is reduced: 2 H+ + 2 e− → H2 (reduction), so H goes +1 → 0.