Calculation of Change in EMF for Dilution of Zn2/Zn Electrode

Heading: Definition of Electrode Dilution

Electrode dilution refers to the process of decreasing the concentration of an electrode solution by adding a solvent such as water. This is usually done to prepare a solution with a lower concentration for use in electrochemical experiments.

Heading: Effect of Dilution on EMF

When an electrode solution is diluted, the concentration of ions in the solution decreases. This results in a decrease in the activity of the ions, which in turn affects the emf of the electrode. The emf of an electrode is directly proportional to the activity of the ions in the solution.

Heading: Calculation of Change in EMF for Zn2/Zn Electrode Dilution

The emf of a Zn2/Zn electrode is given by the Nernst equation:

E = E° - (RT/nF) ln(Q)

where E is the emf, E° is the standard emf, R is the gas constant, T is the temperature, n is the number of electrons transferred in the reaction, F is the Faraday constant, and Q is the reaction quotient.

For the Zn2/Zn electrode, the reaction is:

Zn2+ + 2e- -> Zn

The standard emf for this reaction is -0.76 V.

If the Zn2/Zn electrode solution is diluted 100 times, the concentration of Zn2+ ions will be decreased by a factor of 100. This means that the reaction quotient Q will also be decreased by a factor of 100.

Using the Nernst equation, we can calculate the new emf of the electrode:

E' = E° - (RT/nF) ln(Q/100)

E' = -0.76 V - (0.0257 V/K)(298 K/2)(ln(1/100))

E' = -0.76 V - (-0.0295 V)

E' = -0.7305 V

The change in emf is:

ΔE = E' - E

ΔE = -0.7305 V - (-0.76 V)

ΔE = 0.0295 V

Therefore, the answer is option c) increase of 29.5mV.