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Use the References to access important values if needed for this question. Enter

ID: 1019158 • Letter: U

Question

Use the References to access important values if needed for this question. Enter electrons as e-. Use smallest possible integer coefficients. States are not required. If a box is not needed, leave it blank. An aqueous SnI2 solution is electrolyzed under 1 bar pressure using platinum electrodes.

(a) Write the half-reactions predicted to occur at the anode and cathode, based on the standard cell potentials given below. Standard Reduction Potentials (Volts) at 25 °C

I2(s) + 2 e- 2 I-(aq) 0.535

O2(g) + 4 H3O+(aq) + 4 e- 6 H2O(l) 1.229

2 H2O(l) + 2 e- H2(g) + 2 OH-(aq) -0.828

Sn2+(aq) + 2 e- Sn(s) -0.140

Half-reaction at anode:

Half-reaction at cathode:

(b) What is the expected decomposition potential? V

Explanation / Answer

anode half reaction :

Sn (s) -------------------> Sn+2 (aq) + 2e-

cathode half reaction:

I2 (s) + 2e- -----------------> 2I- (aq)

b)

decomposition potential = Eo cathode - Eo anode

= 0.535 - (-0.140)

= 0.675 V