Question

The standard EMF of a cell having one electron change is found to be 0.591 V at 25°CThe equilibrium constant of the reaction is:

• A. 1.0×10³⁰
• B. 1.0×10⁵
• C. 1.0×10¹⁰
• D. 1.0×10¹

Answer 1

Answer: (C)

1.0 × 10¹⁰

Answer 2

The relationship between the standard EMF ($E^\circ_{cell}$) and the equilibrium constant (K) of a reaction at 25°C is given by the Nernst equation at equilibrium:

$E^\circ_{cell} = \frac{0.0591}{n} \log K$

Where:

$E^\circ_{cell}$ = Standard EMF of the cell n = Number of electrons involved in the reaction K = Equilibrium constant

Given:

Standard EMF ($E^\circ_{cell}$) = 0.591 V Number of electrons (n) = 1 Temperature = 25°C

Substitute the given values into the equation:

$0.591 = \frac{0.0591}{1} \log K$

$0.591 = 0.0591 \log K$

To find $\log K$, divide both sides by 0.0591:

$\log K = \frac{0.591}{0.0591}$

$\log K = 10$

To find K, take the antilog of 10:

$K = 10^{10}$

Therefore, the equilibrium constant of the reaction is $1.0 \times 10^{10}$.