Page No 73: - Chapter 3 - Electrochemistry - Intext Solutions - Ncert Solutions class 12 - Chemistry

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Question 3.4:

Calculate the potential of hydrogen electrode in contact with a solution whose pH is 10.

Answer:

For hydrogen electrode,  , it is given that pH = 10

∴[H⁺] = 10⁻¹⁰ M

Now, using Nernst equation:

=   

= −0.0591 log 10¹⁰

= −0.591 V

Question 3.5:

Calculate the emf of the cell in which the following reaction takes place:

Given that  = 1.05 V

Answer:

Applying Nernst equation we have:

= 1.05 − 0.02955 log 4 × 10⁴

= 1.05 − 0.02955 (log 10000 + log 4)

= 1.05 − 0.02955 (4 + 0.6021)

= 0.914 V

Question 3.6:

The cell in which the following reactions occurs:

has

= 0.236 V at 298 K.

Calculate the standard Gibbs energy and the equilibrium constant of the cell reaction.

Answer:

Here, n = 2,   T = 298 K

We know that:

= −2 × 96487 × 0.236

= −45541.864 J mol⁻¹

= −45.54 kJ mol⁻¹

Again,  −2.303RT log K_c

= 7.981

∴K_c = Antilog (7.981)

= 9.57 × 10⁷