Which of the following does NOT affect the rate of a chemical reaction?

• A. The color of the reactants
• B. The presence of a catalyst
• C. The temperature of the system
• D. The concentration of reactants

Answer: (A)

Verified step by step guidance

1. Understand that the rate of a chemical reaction depends on factors that influence how often and how effectively reactant molecules collide and react.
2. Recall that the concentration of reactants affects the reaction rate because higher concentration means more molecules per unit volume, leading to more frequent collisions.
3. Recognize that temperature affects reaction rate by increasing the kinetic energy of molecules, which increases both collision frequency and the energy with which molecules collide, making reactions faster.
4. Know that the presence of a catalyst affects the reaction rate by providing an alternative reaction pathway with a lower activation energy, thus speeding up the reaction without being consumed.
5. Identify that the color of the reactants does not influence the rate of reaction because color is a physical property related to light absorption and does not affect molecular collisions or energy directly.