Q21E - Organic Chemistry (Mcmurry)

Question

Draw an energy diagram for a two-step reaction with ${\mathbf{K}}_{\mathrm{eq}}$ > 1. Label the overall ${\mathbf{\Delta G}}^o$, transition states, and intermediate. Is ${\mathbf{\Delta G}}^o$ positive or negative?

Step-by-Step Solution

Answer

                                  ${\mathbf{\Delta G}}^o\mathbf{ }\mathbf{For}\mathbf{ }\mathbf{the}\mathbf{ }\mathbf{reaction}\mathbf{ }\mathbf{is}\mathbf{ }\mathbf{negative}$

Step 1: Energy profile diagram

An energy profile diagram is a plot of energy against the reaction coordinate. This shows when the reaction proceeds how the energy of the reactant and product changes.

Step 2: Relation between K eq and exergonic reaction

When ${\mathbf{K}}_{\mathrm{eq}}$  greater than 1 then the energy is out in the reaction which means the reaction is exergonic.

When ${\mathbf{K}}_{\mathrm{eq}}$ less than 1 is then the energy is in the reaction which means the reaction is endergonic.

If  ${\mathbf{K}}_{\mathrm{eq}}$> 1 then ${\mathbf{\Delta G}}^o$ is negative.

Step 3: Energy profile diagram showing K eq > 1

If  ${\mathbf{K}}_{\mathrm{eq}}$> 1 then ${\mathbf{\Delta G}}^o$ is negative as shown in the following diagram.