Which of the following best explains why a catalyst allows a chemical reaction to occur at 0 °C?

• A. The catalyst provides additional reactants for the reaction.
• B. The catalyst increases the temperature of the reactants.
• C. The catalyst lowers the activation energy required for the reaction.
• D. The catalyst changes the equilibrium position of the reaction.

Answer: (C)

Verified step by step guidance

1. Understand the role of a catalyst in a chemical reaction: a catalyst provides an alternative reaction pathway with a lower activation energy, which allows the reaction to proceed faster or at lower temperatures.
2. Recall that activation energy is the minimum energy required for reactants to transform into products; lowering this energy barrier means more molecules have enough energy to react even at lower temperatures like 0 °C.
3. Recognize that a catalyst does not provide additional reactants; it only affects the rate of the reaction by changing the energy pathway, not the amount of reactants available.
4. Note that a catalyst does not increase the temperature of the reactants; temperature is an external condition and is not altered by the presence of a catalyst.
5. Understand that a catalyst does not change the equilibrium position of a reaction; it only helps the system reach equilibrium faster by speeding up both the forward and reverse reactions equally.