Question

what change would most likely decrease the rate of a chemical reaction within a mixture?

reducing the mass of the mixture.

placing the mixture into a heated oven.

placing the mixture in a freezer.

stirring the mixture.

Explanation:

• Reducing the mass of the mixture doesn't directly affect the reaction rate as it's about the amount of substance, not the reaction - related factors like temperature or particle movement.
• Placing the mixture into a heated oven increases the temperature. According to the collision theory, higher temperature means more kinetic energy for particles, leading to more frequent and energetic collisions, thus increasing the reaction rate.
• Stirring the mixture increases the frequency of particle collisions (by better mixing), which increases the reaction rate.
• Placing the mixture in a freezer lowers the temperature. Lower temperature means less kinetic energy for particles. Fewer and less energetic collisions occur (based on collision theory), which decreases the reaction rate.

Answer:

Placing the mixture in a freezer.