KCET 2025 Chemistry Paper

For the half-cell reaction Al3++3e−⟶Al( s), consider the Nernst equation:
E‌Red ‌=E‌Red ‌o−‌

0.0591

3

‌log‌

[Al( s)]

[Al3+]

Since the active mass of a solid is constant and equal to 1 , the equation simplifies to:
E‌Red ‌=E‌Red ‌o−‌

0.0591

3

‌log‌

1

[Al3+]

This further simplifies to:
E‌Red ‌=E‌Red ‌o+‌

0.0591

3

‌log[Al3+]
From this equation, it's clear that E‌Red ‌ is directly proportional to [Al3+]. Thus, as the concentration of Al3+ increases, the electrode potential increases.