Question

For the following concentration cell: Mg(s) | Mg²⁺(0.24 M) | Mg²⁺(0.53 M) | Mg(s)
(a) Determine the initial emf (Δε) for this cell (in volts)
(b) Determine the concentration of Mg²⁺ in each cell when the emf of this cell goes to 0 volts
T = 298 K T = 310 K

Answer 1

For the following concentration cell: Mg(s) | Mg²⁺(0.24 M) | Mg²⁺(0.53 M) | Mg(s)
(a) Determine the initial emf (Δε) for this cell (in volts)
(b) Determine the concentration of Mg²⁺ in each cell when the emf of this cell goes to 0 volts
T = 298 K T = 310 K

We use the Nernst Equation:

E cell = E*cell - (RT/nF)(ln [dilute]/[concentrated])

E cell = 0 - [(8.314 J/mol-K)(298) / (2 mol e-)(96500 J/V-mol e-)] x [ln (0.24/0.53)]

E cell = - (0.01284) (-0.79 )

=+ 0.0101 V

(b) Determine the concentration of Mg²⁺ in each cell when the emf of this cell goes to 0 volts

T = 298 K T = 310 K

Then the concentration in [dilute] = [concentrated

At T = 298 K

We use the Nernst Equation:

E cell = E*cell - (RT/nF)(ln [dilute]/[concentrated])

E cell = 0 - [(8.314 J/mol-K)(298) / (2 mol e-)(96500 J/V-mol e-)] x [ln 1.0]

E cell = 0 - [(8.314 J/mol-K)(298) / (2 mol e-)(96500 J/V-mol e-)] x 0

= 0