Draw an energy diagram for a one-step reaction with Keq<1 . Label the parts of the diagram corre

Draw an energy diagram for a one-step reaction with Keq<1 ....

Key Concepts

Transition State

The transition state is the highest energy point along the reaction coordinate on the energy diagram. It represents the unstable configuration of atoms at the peak of the energy barrier that reactants must overcome to form products. This state, though fleeting, is critical for determining the reaction’s rate and mechanism.

Energy Diagram

An energy diagram is a graph that plots the free energy of a system as it progresses along the reaction coordinate, depicting the energetic changes from reactants to products. It visually represents key features such as the starting energy of the reactants, the energy peak (transition state), and the energy level of the products, providing insight into the kinetics and thermodynamics of the reaction.

Activation Free Energy (?G†)

Activation free energy is the energy difference between the reactants and the transition state. It is the barrier that must be overcome for the reaction to proceed and directly influences the reaction rate; a higher ?G† means a slower reaction under similar conditions.

Standard Reaction Free Energy (?G°)

Standard reaction free energy is the difference in free energy between the products and reactants under standard conditions. It indicates the overall thermodynamic favorability of the reaction. If ?G° is negative, the reaction is thermodynamically favorable (exergonic); if it is positive, as in the case with a small equilibrium constant (K_eq < 1), the reaction is unfavorable (endergonic).

Equilibrium Constant (K_eq) and its Relation to ?G°

The equilibrium constant, K_eq, describes the ratio of the concentrations of products to reactants at equilibrium. Its relationship with standard reaction free energy is given by the expression ?G° = -RT ln K_eq. Thus, when K_eq is less than one, indicating that reactants are favored at equilibrium, ?G° is positive, signifying a thermodynamically uphill (endergonic) process.

Transcript

00:01 In this question, we are going to label the parts of an energy diagram given that the equilibrium constant is less than one.

00:10 So let's write a generalize equilibrium reaction.

00:15 So we have the reactants and the products.

00:31 So the equilibrium constant is equal to the product of the concentrations of the reactants.

00:42 So these are the reactants and it's raised to the power of the coefficient in the balance equation.

00:54 So the product of these two products and divided by the reactants.

01:11 And here, in our question, the equilibrium constant is less than one.

01:24 And when this happens, the forward reaction is unfavorable.

01:29 And the reaction favors the formation of the reactants over the products.

01:39 So when the equilibrium constant is less than one, the reaction is endogonic, and therefore, the change in free energy will be positive.

02:14 So recall that the change in, recall that the change in free energy of the reaction is equal to the free energy of the products minus the free energy of the reactants.

03:12 So therefore, for delta g, the changing free energy of the reaction to be positive, the free energy of the product, the free energy of the product.

03:24 Needs to be greater than the free energy of the reactants.

03:30 So now let's draw the energy diagram.

03:46 So this will be our energy diagram...

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