Which of the following changes would generally NOT increase the reaction rate?

Decreasing catalyst concentration would generally not increase the reaction rate because catalysts are substances that speed up chemical reactions without being consumed in the process. They work by providing an alternative reaction pathway with a lower activation energy, which increases the rate of reaction. Therefore, reducing the amount of catalyst available means there would be fewer active sites for the reaction to occur, leading to a slower reaction rate. In contrast, increasing temperature, smaller particle sizes, and higher reactant concentrations all contribute to increased reaction rates through enhanced kinetic energy, greater surface area, or more frequent collisions between reactant particles.