Question

A catalyst increases the rate of reaction because it:
(A) increases the activation energy
(B) decreases the activation energy
(C) decreases collision diameter
(D) increases the temperature coefficient

Answer 1

Hint: A catalyst is a substance that can be added to a reaction to increasing the reaction rate without getting consumed in the process. This minimum energy with which molecules must be moving in order for a collision to result in a chemical reaction is known as the activation energy.

Complete step by step solution:
Catalysts typically speed up a reaction by reducing the activation energy or changing the reaction mechanism. Enzymes are proteins that act as catalysts in biochemical reactions.
During chemical reactions, certain chemical bonds are broken and new ones are formed. For example, when a glucose molecule is broken down, bonds between the carbon atoms of the molecule are broken. Since these are energy-storing bonds, they release energy when broken. However, to get them into a state that allows the bonds to break, the molecule must be somewhat contorted.
The presence of a catalyst increases the reaction rate (in both forward and reverse reactions) by providing an alternative pathway with lower activation energy. If the activation energy is lowered, more reactants can cross that barrier easily and so, the rate of reaction increases.

Therefore, the correct answer is the (B) option.

Note: Even if two molecules collide with sufficient activation energy, there is no guarantee that the collision will be successful. In fact, the collision theory says that not every collision is successful, even if molecules are moving with enough energy. The reason for this is because molecules also need to collide with the right orientation so that the proper atoms line up with one another, and bonds can break and reform in the necessary fashion.