Take R = 8.314 J mol^-1 K^-1. A reaction has K = 1.5 x 10^-3 at 400 K and K = 4.8 x 10^-2 at 450 K. Assuming Delta H deg is independent of temperature, calculate Delta H deg in kJ mol^-1 (nearest integer).

JEE Main levelNumerical answerDifficulty 2 of 3ce138

Take $R = 8.314 J mo l^{- 1} K^{- 1}$ . A reaction has $K = 1.5 \times 1 0^{- 3}$ at $400 K$ and $K = 4.8 \times 1 0^{- 2}$ at $450 K$ . Assuming $Δ H^{\circ}$ is independent of temperature, calculate $Δ H^{\circ}$ in $kJ mo l^{- 1}$ (nearest integer).

Numerical answer type, answer in kJ/mol, tolerance 1.

ln (K_{2} / K_{1}) = ln (32) = 3.4657

and

1/400 - 1/450 = 2.7778 \times 1 0^{- 4} K^{- 1}

Δ H^{\circ} = 8.314 \times 3.4657/2.7778 \times 1 0^{- 4} = 103731 J mo l^{- 1}

, i.e. about 104 kJ/mol (positive, as

K

rises with

T