Final answer:
A catalyst increases the rate of a chemical reaction by providing an alternate pathway with lower activation energy and by increasing the probability of reactants having the correct orientation to react.
Step-by-step explanation:
There are two main ways a catalyst affects a chemical reaction. First, it increases the rate of the reaction by providing an alternative pathway for the reaction with a lower activation energy. This lower activation energy means that more reactant molecules have sufficient energy to undergo the reaction, leading to an increased rate of reaction. The second way is by increasing the likelihood of reactants having the proper orientation to react with each other, due to the catalyst facilitating the proper alignment of the reacting molecules.
Catalysts are especially crucial in living organisms, where highly specialized catalysts called enzymes work to regulate reactions under the controlled conditions of pH and body temperature required for life processes. In summary, a catalyst is a substance that is not consumed in the reaction and helps the reaction to reach equilibrium more quickly without altering the position of the equilibrium.