Take R = 8.314 J mol^-1 K^-1. At 300 K, reaction 1 has Delta G_1 deg = +30.0 kJ mol^-1 and reaction 2 has Delta G_2 deg = -50.0 kJ mol^-1. They are added to give an overall reaction 3 with equilibrium constant K_3. Which statements are correct?

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3ce164

Take $R = 8.314 J mo l^{- 1} K^{- 1}$ . At $300 K$ , reaction 1 has $Δ G_{1}^{\circ} = + 30.0 kJ mo l^{- 1}$ and reaction 2 has $Δ G_{2}^{\circ} = - 50.0 kJ mo l^{- 1}$ . They are added to give an overall reaction 3 with equilibrium constant $K_{3}$ . Which statements are correct?

K = e^{- Δ G^{\circ} / RT}

with

RT = 2494.2 J mo l^{- 1}

. This gives

K_{1} = 6.0 \times 1 0^{- 6}

and

K_{2} = 5.1 \times 1 0^{8}

(not its reciprocal, since

Δ G_{2}^{\circ}

is negative). Free energies add,

Δ G_{3}^{\circ} = - 20.0 kJ mo l^{- 1}

, so equilibrium constants multiply:

K_{3} = K_{1} K_{2} = 3.0 \times 1 0^{3}

, not the sum.