Given that [Al³⁺] = 1.00 x 10^-2 M, what is the reduction potential for the following half-reaction:

Al³⁺ (aq) + 3 e^- → Al (s)?

Data: E⁰_red [Al³⁺] = - 1.66 V at 25°C

Question

Given that [Al³⁺] = 1.00 x 10^-2 M, what is the reduction potential for the following half-reaction:

Al³⁺ (aq) + 3 e^- → Al (s)?

Data: E⁰_red [Al³⁺] = - 1.66 V at 25°C

| General Chemistry 3

Accepted Answer

Nernst equation:

At 25°C:

E_red = E⁰_red – $\frac{RT}{ν_{e} F}$ x ln Q = E⁰_red – $\frac{0.02570}{ν_{e}}$ x ln Q

E_red = reduction potential (in V) E⁰_red = -1.66V ν_e = stoichiometric coefficient of the electrons = 3 Q = reaction quotient = 1 / [Al³⁺]

E_red = E⁰_red –

\frac{0.02570}{ν_{e}}

x ln Q

E_red = - 1.66 +

\frac{0.02570}{3}

x ln 0.200

E_red = - 1.70 V

Exercise 4 | Electrochemistry