1. Which of the following half-reactions is involved in the STANDARD HYDROGEN EL
ID: 961947 • Letter: 1
Question
1. Which of the following half-reactions is involved in the STANDARD HYDROGEN ELECTRODE?
a. Pt2+(aq) + 2e- à Pt(s)
b. 2H3O+(aq) + 2e- à 2H2O(l) + H2(g)
c. H2O2(aq) + 2H3O+(aq) + 2e- à 4H2O(l)
d. O2(g) + 2H2O(l) + 4e- à 4OH-(aq)
e. None of the above.
2. When a metal and non-metal react, the metal becomes a(n) ____________ and the non-metal becomes a(n)_____________. The metal is _________________ and the non-metal is _____________. Metals are therefore ____________ and non-metals are __________.
a. cation; anion; reduced; oxidized; reducing agents; oxidizing agents
b. cation; anion; oxidized; reduced; reducing agents; oxidizing agents
c. cation; anion; oxidized; reduced; oxidizing agents; reducing agents
d. anion; cation; reduced; oxidized; reducing agents; oxidizing agents
e. anion; cation; oxidized; reduced; reducing agents; oxidizing agents
3. Which reaction correctly describes the electro-chemical cell shown? The cell is at standard conditions. The salt bridge contains sodium sulfate.
a. 3Cu2+ (aq) + 2Al+3 (aq) à 3Cu (s) + 2Al (s)
b. 3Cu2+ (aq) + 2Al (s) à 3Cu (s) + 2Al3+ (aq)
c. 3Cu(s) + 2Al (s) à 3Cu2+ (aq) + 2Al+3 (aq)
d. 2Cu2+ (aq) + 3Al (s) à 2Cu (s) + 3Al+3 (aq)
e. 2Cu(s) + 3Al+3 (aq) à 2Cu2+ (aq) + 3Al (s)
Explanation / Answer
The following half-reactions is involved in the STANDARD HYDROGEN ELECTRODE
2H+(aq) + 2e H2(g) or
b. 2H3O+(aq) + 2e- à 2H2O(l) + H2(g)
2. When a metal and non-metal react, the metal becomes a(n) ____________ and the non-metal becomes a(n)_____________. The metal is _________________ and the non-metal is _____________.
The correct answers is cation; anion; oxidized; reduced; reducing agents; oxidizing agents
Because Metal formed cation after loosing e-, and thus the oxidation number of metals increased means they are oxidized. The metals are reducing agents because they provide e- for reduction.
The following reaction correctly describes the electro-chemical cell
3Cu2+ (aq) + 2Al (s) ---- > 3Cu (s) + 2Al3+ (aq)
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