Using what you have learned about changes in Gibbs free energy, would you predict the ∆G value of catabolic reactions to be positive or negative? What about anabolic reactions? Justify your answers using the terms 'enthalpy' and 'entropy.'

Video transcript

Hi everyone. Let's look at our next question, What is the value of gibbs free energy when the reaction is spontaneous as we recall, a spontaneous reaction means it's going to take place without any outside force causing it to take place? Well, gibbs free energy comes with an equation. Delta G equals delta H minus T. Delta S. Delta G. Mean the change in gibbs free energy and we recall these variables here, H is the change. So delta H. Is the change in entropy T. Is temperature in kelvin and delta S. Is a change in entropy and entropy. We can think of as sort of the energy content of whether it's our reactant or our products sort of thermodynamic potential and the change in entropy DELTA H at constant pressure is equal to the amount of heat evolved during the reaction. So either released or absorbed. And it's important remember that if Pete is released, delta H will be negative and that's because its products will have a lower sort of energy potential than its react ints. Entropy. Is that measure of disorder? As we know by the second law of thermodynamics, um the universe tends in a direction to increase entropy. So if we're talking about a reaction taking place spontaneously, um a favorable entropy change will be if delta S. Is positive, DELTA S. Is positive, that means the entropy of the products is higher, then the entropy of the reactant. So these two factors, um what's happening to energy content of the system and what's happening to the entropy? Those reactions and products both sort of determine if that reaction is going to take place spontaneously. So, if we think about this, we want to look at uh entropy heat being released will be spontaneous. So that would be a negative value. And we would subtract entropy, which if it's going to be a favorable reaction, we'd want to see an increase in entropy. So delta G. Is negative. If delta G is negative, our reaction will be spontaneous. And this reflects a sort of loss of energy potential of the system. Because we can think of um Gibbs free energy as a potential of a system to do work so far Delta G as negative. Our reactant since can have greater potential to do work than our products. So, a negative delta G reflects a spontaneous reaction. So that is when we look at our answer choices, that's choice D. Negative. So again, what is the vibe Gibbs free energy. When the reaction is spontaneous choice, the negative