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] = 0.750 M, [CH3C5H9] = 0.250 M
B
[C6H12] = 0.500 M, [CH3C5H9] = 0.500 M
C
[C6H12] = 0.875 M, [CH3C5H9] = 0.125 M
D
[C6H12] = 0.143 M, [CH3C5H9] = 0.857 M
Verified step by step guidance1
Identify the initial concentrations: [C6H12] = 1.0 M and [CH3C5H9] = 0 M.
Define the change in concentration at equilibrium: Let x be the change in concentration of C6H12 that converts to CH3C5H9. Therefore, at equilibrium, [C6H12] = 1.0 - x and [CH3C5H9] = x.
Write the expression for the equilibrium constant Kc: Kc = [CH3C5H9] / [C6H12]. Substitute the equilibrium concentrations into this expression: Kc = x / (1.0 - x).
Substitute the given value of Kc (0.143) into the equation: 0.143 = x / (1.0 - x).
Solve the equation for x to find the equilibrium concentrations: Rearrange the equation to solve for x, which represents the concentration of CH3C5H9 at equilibrium. Then, calculate [C6H12] = 1.0 - x.
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