Question

which statement best describes how a catalyst can speed up a chemical reaction?
○ the catalyst decreases the activation energy needed.
● the catalyst increases the concentration of products.
○ the catalyst binds to enzymes to release substrates.
○ the catalyst increases the concentration of reactants.

Explanation:

To determine the correct statement about how a catalyst speeds up a chemical reaction, we analyze each option:

1. "The catalyst decreases the activation energy needed."

Catalysts work by providing an alternative reaction pathway with a lower activation energy. This allows more reactant particles to have enough energy to react, thus increasing the reaction rate. This is a fundamental principle of catalysis.

1. "The catalyst increases the concentration of products."

Catalysts do not affect the equilibrium concentrations of products (or reactants). They only speed up the rate at which equilibrium is reached, so this is incorrect.

1. "The catalyst binds to enzymes to release substrates."

This describes a specific interaction (e.g., enzyme - substrate interactions) but is not a general mechanism for how catalysts speed up reactions. Most catalysts are not enzymes, and this is not the core mechanism of catalysis.

1. "The catalyst increases the concentration of reactants."

Catalysts do not change the concentration of reactants. They affect the energy barrier (activation energy) for the reaction, not the amount of reactants present.

Answer:

The catalyst decreases the activation energy needed.