Short Answer

Temperature affects reaction rate by changing how fast particles move. When temperature increases, particles gain more energy, move faster, and collide more often and with greater force. This increases the chances of successful collisions, causing the reaction to happen more quickly.

When temperature decreases, particles move slowly and collide less frequently. As a result, the reaction rate becomes slower. This is why food spoils faster in hot weather and stays fresh longer in the refrigerator. Temperature is one of the most important factors controlling the speed of chemical reactions.

Detailed Explanation :

Effect of Temperature on Reaction Rate

Temperature plays a major role in determining how fast or slow a chemical reaction occurs. All chemical reactions depend on the collision of particles—atoms, molecules, or ions. For a reaction to occur, particles must collide with enough energy to break existing bonds and form new ones. Temperature directly affects both the movement of particles and the energy with which they collide.

When temperature increases, reactant particles absorb heat energy. This extra energy allows them to move faster, collide more often, and collide with greater energy. As a result, the likelihood of successful collisions increases, and the reaction proceeds more rapidly. On the other hand, lowering temperature slows particle movement, reduces the energy of collisions, and decreases the reaction rate.

Understanding how temperature affects reaction rate is important in industries, cooking, food preservation, environmental processes, and everyday activities.

1. Increase in Kinetic Energy

Temperature increases the kinetic energy of particles.

• At higher temperatures, particles move faster.
• They collide more frequently.
• A larger number of collisions have enough energy to overcome activation energy.

This leads to a faster reaction.

Example

When hydrogen peroxide is heated, it decomposes faster because the molecules move more energetically.

2. More Frequent and Energetic Collisions

At higher temperatures:

• Collisions occur more often.
• Collisions occur with greater force.
• More collisions reach the activation energy threshold.

Only collisions with sufficient energy result in chemical change. Higher temperature increases the number of such collisions.

Example

Burning wood is easier when heat is supplied because more molecules collide with enough energy to react.

3. Effect on Activation Energy

Activation energy is the minimum energy needed for a reaction to start.

Higher temperature does not change activation energy itself but:

• Increases the number of particles that have enough energy to cross the activation energy barrier.
• Boosts the reaction rate, even if the activation energy is high.

Example

Food cooks faster on a high flame because more molecules can react at once.

4. Temperature and Reaction Speed

High Temperature → Fast Reaction

• More energy
• Faster movement
• More successful collisions
• Reaction completes quickly

Low Temperature → Slow Reaction

• Less energy
• Slower movement
• Fewer successful collisions
• Reaction progresses slowly

Examples

• Milk spoils rapidly in summer (fast reactions).
• Milk stays fresh in the fridge (slow reactions).
• Rusting increases in warm, humid conditions.
• Cold weather slows decomposition of organic matter.

5. Temperature Coefficient (Q10 Effect)

Many reactions roughly double in rate for every 10°C increase in temperature.
This is known as the Q10 rule and is especially true in biological systems.

Example

Enzyme-catalyzed reactions in the body work much faster at slightly higher temperatures but slow down if temperature drops.

6. Practical Applications of Temperature Control

Understanding temperature’s effect helps in controlling reactions in multiple areas:

Cooking

Heating speeds up chemical changes in food.

Refrigeration

Lower temperature slows bacterial reactions, preserving food.

Industrial Manufacturing

Rate of production increases with temperature, but overheating must be avoided for safety.

Medicines

Drugs degrade slowly at low temperatures, maintaining effectiveness.

Environmental Science

Temperature affects the rate at which pollutants break down.

Combustion

Fuels burn faster at higher temperatures, producing more energy.

Conclusion

Temperature affects reaction rate by controlling the energy and movement of particles. Higher temperature increases kinetic energy, causes more frequent and energetic collisions, and results in a faster reaction. Lower temperature slows particle motion and reduces the number of successful collisions, slowing the reaction rate. Because of these effects, temperature is one of the most important factors in chemistry, industry, food science, biology, and daily life.