Question

What is the effect of catalyst on:
1. Gibbs energy
2. Activation energy of reaction

Answer 1

Hint: We know that catalysts are compounds that accelerate the rate of a reaction. Gibbs free energy is independent of the path of the transformation and is unaffected by the mechanism of a reaction. And about activation energy, it is the energy difference between the reactants and the activated complex.

Complete step-by-step answer:
We should know about catalysts that are substances that can be added to a reaction to increase the reaction rate without getting consumed in the process. If we add a catalyst to chemical reaction then chemical reactions occur faster because the catalyst provides an alternative reaction pathway.
For chemicals to react, their bonds must be rearranged, because the bonds in the products are different from those in the reactants. The slowest step in the bond rearrangement produces what is termed a transition state - a chemical species that is neither a reactant nor a product, but is an intermediate between the two.
\[Reactant\rightleftarrows Transition\text{ }State\rightleftarrows Product\]
Energy is required to form the transition state. This energy is called the activation energy, or \[{{E}_{a}}\]. We can think of activation energy as a barrier to a chemical reaction, a hurdle that must be crossed. If the barrier is high, few molecules have sufficient kinetic energy to collide, form a transition state, and cross the barrier. Reactants with energy lower than \[{{E}_{a}}\] cannot pass through the transition state to react and become products.
A catalyst works by providing a different route, with lower\[{{E}_{a}}\], for the reaction. Catalysts lower the energy barrier. The different route allows the bond rearrangements needed to convert reactants to products to take place more easily, with a lower energy input.
For example in the Haber Process: We know that the Haber process, is used to make ammonia from hydrogen and nitrogen, is catalysed by iron, which provides atomic sites on which the reactant bonds can rearrange more easily to form the transition state.
\[{{N}_{2}}\left( gas \right)+\text{ }3{{H}_{2}}\left( gas \right)\rightleftharpoons 2N{{H}_{3}}\left( gas \right)\]
Now, we will know the effect of catalyst on Gibbs energy. We should know that Gibbs free energy change is a state function which does not depend upon the path taken by the reaction, it depends only on enthalpy and entropy(state functions) of the reaction which in turn depends upon reactants and products only .
If we think this in the terms of equilibrium, adding of catalyst does not change the equilibrium of a reaction (shifted by temperature) and the equilibrium is the property of Gibbs free energy,
\[~\to G=-RT\text{ }ln\text{ }K\], which remains constant (at constant temperature).
So, from above discussion now we know that the only effect of the catalyst is to lower the activation energy of the reaction. The catalyst does not affect enthalpy, entropy and temperature remain the same therefore there is no effect on Gibbs free energy .

Note: We should know that in biology, enzymes are protein-based catalysts in metabolism and catabolism. Most catalysts are enzymes.
We should also know that substances that reduce the action of catalysts are called catalyst inhibitors. Promoters are substances that increase the catalytic activity, even though they are not catalysts by themselves. Inhibitors are sometimes referred to as "negative catalysts" since they decrease the reaction rate. They do not work by introducing a reaction path with higher activation energy; instead the reaction would continue to occur by the non-catalysed path. Instead they act either by deactivating catalysts, or by removing reaction intermediates such as free radicals.