Answer:
A catalyst is C. not used up in a reaction.
Explanation:
A catalyst is a substance capable of promoting or accelerating a chemical reaction without directly intervening in it. That is to say that at the end of the reaction the catalyst remains unchanged. Therefore, it is not considered as a reagent or product according to the stoichiometry of the reaction.
Catalysts that are responsible for increasing the speed of a chemical reaction are called positive catalysts and are the most common and used. But there are also negative catalysts, also known as inhibitory catalysts. These reduce the speed of a reaction.
Catalysts can be classified into:
- Homogeneous: this catalyst is dissolved with those reagents that are in the same phase.
- Electrocatalyst: is that used to improve the speed of semi-reaction of batteries that work as fuel.
- Heterogeneous: also known as contact, it is characterized by not being in the same stage as the reagents.
- Biological: also known as enzyme, they are proteins whose main function is to accelerate the speed in biochemical reactions.
Finally, the correct answer is a catalyst is not used up in a reaction.
