Which of the following is true of heterogeneous catalysts?

• A. They are in a different phase than the reactants.
• B. They must be dissolved in the reaction mixture.
• C. They are consumed during the reaction.
• D. They increase the equilibrium constant of the reaction.

Answer: (A)

Verified step by step guidance

1. Understand the definition of a heterogeneous catalyst: it is a catalyst that exists in a different phase (solid, liquid, or gas) than the reactants it acts upon.
2. Recall that heterogeneous catalysts typically provide a surface on which reactants adsorb, react, and then desorb as products, without dissolving into the reaction mixture.
3. Recognize that catalysts, whether heterogeneous or homogeneous, are not consumed during the reaction; they remain unchanged and can be used repeatedly.
4. Know that catalysts do not change the equilibrium constant of a reaction; they only speed up the rate at which equilibrium is reached by lowering the activation energy.
5. Conclude that the true statement about heterogeneous catalysts is that they are in a different phase than the reactants.