Question

hich of the following statements are FALSE?

ΔGo > 0 for Br2(l) + 2 Hg(l) ---> 2 Br-(aq) + Hg22+(aq).

ΔGo < 0 for MnO2(s) + SO2(g) ---> Mn2+(aq) + SO42-(aq).

The cell potential for Co(s)|Co2+(aq, 0.1 M)||Fe3+(aq, 1.5 M)|Fe2+(aq,1.5 M)|Pt(s) is less than 1.05 V.

The cell potential for Co(s)|Co2+(aq, 1.5 M)||Fe3+(aq, 0.5 M)|Fe2+(aq, 0.1 M)|Pt(s) is greater than 1.05 V.

The cell potential for Cu(s)|Cu2+(aq, 0.5 M)||Cl2(g, 2.0 atm)|Cl-(aq, 2.0 M)|Pt(s) is equal to 1.02 V.

Answer 1

1.

Br2(l) + 2 e− ⇌ 2 Br− ; E⁰red = 1.066 V

Hg₂²⁺ + 2 e− ⇌ 2 Hg(l) ; E⁰red = 0.80 V

E⁰cell = 1.066 V – 0.8 V > 0

ΔG = - n F E⁰cell < 0

Statement is false.

2.

MnO₂(s) + 4 H⁺ + 2 e− ⇌                Mn²⁺ + 2 H2O ; E⁰red = 1.23 V

SO₄²⁻ + 4 H⁺ + 2 e− ⇌ SO₂(aq) + 2 H₂O ; E⁰red = 0.17 V

E⁰cell = 1.23 V – 0.17 V > 0

ΔG = - n F E⁰cell < 0

Statement is true.

3.

Co²⁺ + 2 e− ⇌ Co(s) ; E⁰red = -0.28 V

2 Fe³⁺ +  2 e− ⇌ 2 Fe²⁺ ; E⁰red = 0.77 V

E⁰cell = 0.77 V + 0.28 V = 1.05 V

Ecell = 1.05 – 0.0592 /2 * log([Co²⁺][ Fe²⁺]² / [Fe³⁺]²)

Ecell = 1.05 – 0.0592 /2 * log([0.1][1.5]² / [1.5]²)

Ecell > 1.05 V

Statement is false.

4.

Co²⁺ + 2 e− ⇌ Co(s) ; E⁰red = -0.28 V

2 Fe³⁺ +  2 e− ⇌ 2 Fe²⁺ ; E⁰red = 0.77 V

E⁰cell = 0.77 V + 0.28 V = 1.05 V

Ecell = 1.05 – 0.0592 /2 * log([Co²⁺][ Fe²⁺]² / [Fe³⁺]²)

Ecell = 1.05 – 0.0592 /2 * log([1.5][0.1]² / [1.5]²)

Ecell > 1.05 V

Statement is true.

5.

Cu²⁺ + 2e− ⇌ Cu(s) ; E⁰red = 0.337 V

Cl₂(g) + 2 e− ⇌ 2 Cl− ; E⁰red = 1.36 V

E⁰cell = 1.36 V - 0.337 V = 1.02 V

Ecell = 1.02 – 0.0592 /2 * log([Cu²⁺][Cl−]² / p(Cl₂))

Ecell = 1.05 – 0.0592 /2 * log([0.5][2]² / (2))

Ecell = 1.02 V

Statement is true.