Multiple Choice
What is the value of the equilibrium constant (K_w) for the autoionization of pure water at 25°C?
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16. Chemical Equilibrium
Equilibrium Constant K
Multiple Choice
Which of the following reactions will have the largest equilibrium constant (K) at 298 K?
A
N_2(g) + 3H_2(g) ightarrow 2NH_3(g)
B
CO(g) + H_2O(g) ightarrow CO_2(g) + H_2(g)
C
H_2(g) + Cl_2(g) ightarrow 2HCl(g)
D
2NO_2(g) ightarrow N_2O_4(g)
Verified step by step guidance1
Step 1: Understand that the equilibrium constant (K) is related to the standard Gibbs free energy change (ΔG°) of the reaction by the equation \(K = e^{-\frac{\Delta G^\circ}{RT}}\), where \(R\) is the gas constant and \(T\) is the temperature in Kelvin.
Step 2: Recognize that a larger equilibrium constant corresponds to a more negative ΔG°, meaning the reaction strongly favors products at equilibrium.
Step 3: For each reaction, identify or look up the standard Gibbs free energies of formation (\(\Delta G_f^\circ\)) for all reactants and products at 298 K.
Step 4: Calculate the standard Gibbs free energy change for each reaction using the formula \(\Delta G^\circ = \sum \Delta G_f^\circ (\text{products}) - \sum \Delta G_f^\circ (\text{reactants})\).
Step 5: Compare the calculated \(\Delta G^\circ\) values for all reactions; the reaction with the most negative \(\Delta G^\circ\) will have the largest equilibrium constant \(K\) at 298 K.
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