Some reactions that are predicted by their sign deltaG to be spontaneous at room temperature do not proceed at a measurable rate at room temperature.

A suitable catalyst increases the rate of such a reaction. What effect does the catalyst have on deltaG for the reaction?

AND

For a reaction, how is the value of the standard free energy change, deltaG, affected by an increase in temperature? Explain.

delta G is delta G. The catalyst lowers the activation energy of the reaction so that it provides an alternative path for the reaction to take place and that allows it to proceed faster but the delta G value remains the same. (The reaction reaches equilibrium faster).

For the second part, what is the equation for delta G?
Delta G = delta H - T*delta S. Now how do you think T will affect delta G?

Would the temperature increase increase the value of delta G then?

Since delta G = delta H - T*delta S, for constant delta S, increasing T will make the right term more negative and that will make delta G more negative. I don't know what you mean by "increasing" delta G, especially when dealing with negative numbers. The safe way to answer this type question is to say that delta G becomes more negative.

okay i see what you're saying. thanks so much for all your help.

Oh, deltaG, my old friend. Well, when it comes to the effect of a catalyst on deltaG, it's an interesting situation. You see, a catalyst doesn't actually have any direct effect on deltaG. It's like an enthusiastic cheerleader of the reaction, just encouraging it to happen faster. So, the catalyst simply increases the rate of the reaction without changing the overall thermodynamics. It's like giving a procrastinator a cup of coffee - it doesn't change their motivation to do something, but it helps them get it done a little quicker.

Now, let's talk about deltaG and temperature. When you crank up the heat, things start to sizzle (literally!). An increase in temperature affects deltaG by altering the balance between the enthalpy and entropy contributions to the overall Gibbs free energy. As temperature rises, the enthalpy contribution tends to dominate, meaning deltaG becomes more sensitive to changes in enthalpy. It's like heating up a soup - the flavors become stronger, enhancing the enthalpy part of the equation. So, as you increase the temperature, deltaG becomes more affected by changes in enthalpy. It's like adding spices to your reaction, making things more exciting!

But remember, deltaG doesn't magically disappear with a change in temperature. It's just the balance of enthalpy and entropy that gets a little shift. So, if you're hoping to find the fountain of spontaneity by messing with temperature, you'll have to keep in mind that the thermodynamics aren't completely turned upside down. It's just a little dance of enthalpy and entropy in the world of deltaG.

To understand the effect of a catalyst on the deltaG (change in Gibbs free energy) for a reaction, let's first understand what deltaG represents. DeltaG is an indicator of the spontaneity of a reaction. If deltaG is negative, it means the reaction is spontaneous (favorable), while a positive value indicates a non-spontaneous (less favorable) reaction.

Now, a catalyst is a substance that increases the rate of a reaction without being consumed itself. It achieves this by providing an alternative reaction pathway with a lower activation energy, allowing the reactants to reach the products more easily. However, it's important to note that a catalyst does not change the deltaG value for a reaction.

The presence of a catalyst affects the rate of the reaction but does not alter the thermodynamics, including deltaG. The catalyst provides an alternative pathway for the reaction, reducing the activation energy, and thus increasing the reaction rate. As a result, the reaction might proceed at a measurable rate at room temperature even though it has a negative deltaG. The catalyst enables the reactants to overcome the energy barrier required for the reaction to occur.

Regarding the effect of temperature on deltaG, a change in temperature affects the value of deltaG. The relationship between temperature and deltaG is described by the equation:

deltaG = deltaH - T * deltaS

Where:
- deltaH is the change in enthalpy (heat absorbed or released)
- deltaS is the change in entropy (measure of disorder/randomness)
- T is the absolute temperature

When the temperature increases, the term -T * deltaS in the equation has a more significant effect. As a result, the magnitude of deltaG decreases. This means that at higher temperatures, reactions with a positive deltaH (endothermic) and a positive deltaS (increase in disorder) are more likely to be spontaneous because the decrease in deltaG outweighs the positive enthalpy term.

Conversely, reactions with a negative deltaH (exothermic) and a negative deltaS (decrease in disorder) will become less spontaneous at higher temperatures because the increase in deltaG becomes more significant, outweighing the negative enthalpy term.