Multiple Choice
Consider the reaction C2H4(g) + H2O(g) -> CH3CH2OH(g). Using the standard thermodynamic data, calculate the equilibrium constant (K) for this reaction at 298.15 K.
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16. Chemical Equilibrium
Equilibrium Constant Calculations
Multiple Choice
Cyclohexane, C6H12, undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane, CH3C5H9, according to the equation: C6H12 ⇌ CH3C5H9. If Kc = 0.143 at 25°C for this reaction and the initial concentration of C6H12 is 1.0 M with no CH3C5H9 present initially, what are the equilibrium concentrations of C6H12 and CH3C5H9?
A
[C6H12] = 0.875 M, [CH3C5H9] = 0.125 M
B
[C6H12] = 0.900 M, [CH3C5H9] = 0.100 M
C
[C6H12] = 0.800 M, [CH3C5H9] = 0.200 M
D
[C6H12] = 0.857 M, [CH3C5H9] = 0.143 M
Verified step by step guidance1
Start by writing the balanced chemical equation for the reaction: \( \text{C}_6\text{H}_{12} \rightleftharpoons \text{CH}_3\text{C}_5\text{H}_9 \).
Define the initial concentrations: \([\text{C}_6\text{H}_{12}] = 1.0 \text{ M}\) and \([\text{CH}_3\text{C}_5\text{H}_9] = 0 \text{ M}\).
Set up an ICE table (Initial, Change, Equilibrium) to track the changes in concentration. Let \(x\) be the change in concentration of \(\text{CH}_3\text{C}_5\text{H}_9\) formed at equilibrium.
Write the expression for the equilibrium constant \(K_c\): \(K_c = \frac{[\text{CH}_3\text{C}_5\text{H}_9]}{[\text{C}_6\text{H}_{12}]}\). Substitute the equilibrium concentrations from the ICE table into this expression.
Solve the equation \(0.143 = \frac{x}{1.0 - x}\) for \(x\) to find the equilibrium concentrations of \([\text{C}_6\text{H}_{12}]\) and \([\text{CH}_3\text{C}_5\text{H}_9]\).
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