Question

Cyclohexane (C6H12) undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane (MCP) according to the equation: C6H12 → MCP If Kc = 0.143 at 25 °C for this reaction, predict the direction in which the system will shift if the initial concentrations of C6H12 and MCP are 0.800 M and 0.400 M, respectively.

multiple choice

The system is already at equilibrium.

is not at equilibrium and will remain in an unequilibrated state.

will shift right.

will shift left.

Answer 1

Answer – We are given reaction C₆H₁₂ -----> MCP , Kc = 0.143

[C₆H₁₂] = 0.800 M , [MCP] = 0.400 M

First we need to calculate the Qc for this reaction and we know Qc is the reaction quotient and there is ratio of the product concentration by reactant concentration at initially.

So, Qc = [MCP] / [C₆H₁₂]

           = 0.400 M / 0.800 M

           = 0.500

We know, when Qc = Kc then reaction at equilibrium there is no shift to either the left or the right.

When Qc < Kc then reaction will shift towards the right side, means reactant side.

When Qc > Kc then reaction will shift towards the left side, means reactant side.

In this problem Kc = 0.143 and Qc = 0.500

So, Qc > Kc then reaction will shift towards the left side, means reactant side.