Question

The equilibrium constant for the conversion of the axial to the equatorial conformation of methoxycyclohexane is 2.7.

1. Given these data, which conformation is present in the larger amount at equilibrium?
2. Is ${\mathbf{\Delta G}}^{\mathbf{°}}$ for this process positive or negative?
3. From the values in Table 6.3, approximate the size of ${\mathbf{\Delta G}}^{\mathbf{°}}$.

Short answer

Answer

1. Equatorial conformation of methoxycyclohexane will be present in higher concentrations at equilibrium.
2. The ${\mathrm{\Delta G}}^{°}$ for this process is negative.
3. The size of ${\mathrm{\Delta G}}^{°}$ lies in the range of 0 to -6.

Step-by-step solution

Step-by-Step SolutionStep 1: Direction of a chemical reaction

A reaction always proceeds in the direction of stable species i.e., a reaction proceeds forward or backward depending on the stability of the reactants and products.

The reaction proceeds forwards only if the products are stable.

Equilibrium constant (Keq)  and free energy change (ΔG°)

A chemical reaction favors the products if its equilibrium constant has a value greater than one.

For a feasible reaction, the free energy change is always negative.

The conformer is present in a larger amount

1. For the given reaction, the equilibrium constant has a value higher than one that indicates that the reaction proceeds forward i.e., towards the direction of equatorial conformation of methoxycyclohexane.
2. Therefore, at equilibrium equatorial methoxycyclohexane will be present in the larger amount.
3. Since the reaction proceeds in the forward direction, the${\mathrm{\Delta G}}^{°}$will have a negative value.
4. The${\mathrm{\Delta G}}^{°}$ value lies in the range of 0 to -6 kJ/mol.