Sketch an energy diagram for a system in which the forward reacti...

Question

Sketch an energy diagram for a system in which the forward reaction has E_act = +25 kcal/mol (+105 kJ/mol) and the reverse reaction has E_act = +35 kcal/mol (+146 kJ/mol).Is the forward process endergonic or exergonic?

Accepted Answer

Welcome back everyone. The activation energies of the forward and reverse reactions of a system are kilojoules per mole or 12 point oh kilos per mole and 75 kilojoules per mole or 17.9 kg per mole respectively. Create an energy diagram for the system and determine whether the forward reaction is either endon or exer. Let's begin by recalling that an ender describes a non spontaneous reaction where the Gibbs free energy change. Delta G is positive or greater than zero. Next, recall that for an ex ergodic process, that process will be spontaneous for our reaction and thus our gibbs free energy change is negative or less than zero. We're going to begin by determining our gibbs free energy change from our prompt. We are given that the activation energy for the forward reaction is equal to 50 kilojoules per mole. And that the activation energy for the reverse reaction is equal to 75 kilojoules per mole. So to determine gibbs free energy change, we would take the difference of the activation energy of our forward reaction. 50 kilojoules per mole subtracted from the activation energy of our reverse reaction. 75 kilojoules per mole. So from this difference of the activation energies, we find a gibbs free energy change that is equal to negative kilojoules per mole. And as we stated, a negative gibbs free energy change corresponds to a spontaneous and ex ergodic reaction. So recall that for a spontaneous exer agonic reaction, the energy of our reactants should be greater than the energy of our products. So drawing out the reaction diagram on our y axis recall that we have a measure of the energy of our reagents and that increases as we go up. Whereas across our x axis, we have a measure of our reaction time. We are given from our pump, the activation energy for the forward reaction or for the reactants equal to 50 kilojoules per mole. So we're going to place our reactants still at a lower point of our Y axis, but at a higher point than our products, and we'll measure that 50 kilojoules per mole of energy would be starting from our origin up to about this point where we have our transition state or first peak of our diagram. And so this measure from our origin of our reactants to the peak or transition state of our reaction represents the activation energy equal to 50 kilojoules per mole. Now, once this, once we reach the transition state of our reaction from the origin of our reactant to the peak of our reaction, our our reactants have gained enough energy in order to be able to form the products. So the reaction will proceed from this peak in a downward direction where our products are formed and lie at a lower energy than our reactants. And notice that from our prompt, the activation energy of our products, from their origin to the transition state or peak of our reaction, which is the activation energy of the reverse reaction is equal to kilojoules per mole. So we have a longer arrow here, double headed arrow. And now thinking of our gibbs free energy change that we calculated, we're going to begin a measure from where our reactants begin to where our products are formed. And from the difference between this double headed arrow, we have our delta G or Gibbs free energy change as we calculated equal to negative 25 kilojoules per mole. So this is our last label that we've had to fill in for our energy diagram. And as a whole, we can confirm that our energy diagram is complete and we were able to determine that we have an ex ergodic reaction since our energy of our reactants was greater than the energy of our products for a spontaneous process. And a gibbs free energy change of negative 25 kilojoules per mole. So our final answer is going to be our complete energy diagram that we were able to construct as well as the confirmation that we have an exer agonic reaction. I hope this made sense and let us know if you have any questions.

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Sketch an energy diagram for a system in which the forward reaction has E_act = +25 kcal/mol (+105 kJ/mol) and the reverse reaction has E_act = +35 kcal/mol (+146 kJ/mol).Is the forward process endergonic or exergonic?

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