Which statement best describes a homogeneous catalyst?

• A. It forms a separate layer that does not mix with the reactants.
• B. It is always a solid while the reactants are gases.
• C. It is consumed during the reaction and cannot be reused.
• D. It is present in the same phase as the reactants.

Answer: (D)

Verified step by step guidance

1. Understand the definition of a catalyst: a substance that increases the rate of a chemical reaction without being consumed in the process.
2. Recognize that catalysts can be classified based on their phase relative to the reactants: homogeneous catalysts are in the same phase, while heterogeneous catalysts are in a different phase.
3. Analyze the options given: a catalyst forming a separate layer or being a solid while reactants are gases suggests a different phase, which corresponds to heterogeneous catalysis.
4. Note that a catalyst is not consumed during the reaction, so the statement about it being consumed and not reusable is incorrect.
5. Conclude that the best description of a homogeneous catalyst is that it is present in the same phase as the reactants.