In an industrial sequence

CHEMISTRY · Multi-part · A Level · Chemistry · Chemical equilibria (Le Chatelier’s principle and Kc) · Chemical equilibria (Le Chatelier’s principle and Kc)

Problem

In an industrial sequence, substance A is first converted to intermediate B, which is then converted to final product C. Both steps occur under standard conditions at

298\,\text{K}

. Step 1:

A \to B

\Delta G^\circ_1 = +15.0\,\text{kJ}\cdot\text{mol}^{-1}

Step 2:

B \to C

\Delta G^\circ_2 = -25.0\,\text{kJ}\cdot\text{mol}^{-1}

(a) Without performing a numerical calculation, predict whether the overall conversion

A \to C

is thermodynamically favored or disfavored at

298\,\text{K}

. Justify your prediction qualitatively. (b) Calculate the standard free-energy change

\Delta G^\circ_3

for the overall reaction

A \to C

and determine its equilibrium constant

K_3

. (c) Rank the equilibrium constants

K_1

K_2

, and

K_3

from largest to smallest. Provide a quantitative justification that connects your ranking to the values obtained in part (b). (d) Suppose both individual steps are carried out in a single reactor so that all three species (A, B, C) are present simultaneously. Discuss how the relative magnitudes of

K_1

K_2

, and

K_3

influence the steady-state concentrations of A, B, and C in the reactor.

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