# Quiz | Electrochemistry

1

Which of the following statements is incorrect?

It is not possible to directly measure the voltage of a single electrode but it can be determined by measuring the voltage difference between a standard electrode and the desired electrode ⇒ in electrochemistry, a Standard Hydrogen Electrode (SHE) is used

2

Which of the following statement about salt bridge is correct?

Salt bridge provides an ionic current path between the 2 solutions with electrodes in order to maintain the charge balance in the cell

3

Why is Standard Hydrogen Electrode (SHE) called as the primary reference electrode?

By convention, the voltage of the SHE is E0 = 0 V ⇒ SHE is the primary reference electrode
2 H+ (aq) + 2 e- → H2 (g)     [E0red = 0 V]

4

What is the reaction of the zinc-copper cell: Zn (s) | ZnSO4(aq) || CuSO4(aq) | Cu(s)?

By convention:
- left-hand electrode: oxidation reaction ⇒ Zn (s) → Zn2+ (aq) + 2 e-
- right-hand electrode: reduction reaction ⇒ Cu2+ (aq) + 2 e- → Cu (s)

5

What is the half-reaction that occurs at the anode during the electrolysis of sodium bromide?

Electrolysis of NaBr: 2 Br- (aq) + 2 Na+ (aq) → Br2 (l) + 2 Na (s)
Anode: oxidation reaction ⇒ 2 Br- → Br2 + 2 e-

6

What is the correct Nernst equation for the reaction: Cu (s) + Zn2+ (aq) → Zn (s) + Cu2+ (aq)?

Nernst equation: E = E0  –  $\frac{\mathrm{RT}}{{\mathrm{\nu }}_{\mathrm{e}}\mathrm{F}}$  ln Q

Cu (s) + Zn2+ (aq) → Zn (s) + Cu2+ (aq) can be broken down into 2 half reaction equations:
Cu (s) → 2 e- + Cu2+ (aq) and Zn2+ (aq) + 2 e- → Zn (s)
⇒ stoichiometric coefficient of the electrons in the 2 half reaction equations νe = 2