iGCSE Rates of Reaction

Rate of reaction

The speed of a reaction.

Why will a chemical reaction occur?

When reactant particles collide with enough energy to react

Increasing the temperature of a reaction by 10°C will

Double the rate.

Activation energy

The minimum amount of energy needed for a reaction to happen. Ea

Adding a catalyst

Increases the rate by providing an alternative reaction path with a lower activation energy

Increasing pressure

More particles in a smaller volume. More frequent collisions.

Increasing concentration

More particles in the same volume of liquid. More frequent collisions.

Increasing temperature

Gives particles more energy. Move faster, collide more frequently. More effective collisions (collisions with energy greater than Ea)

Increasing surface area

Exposes more particles. More frequent collisions.

How can you measure the rate of a reaction?

By experiment. Measure product produced or reactant used up over time.

What does a normal rate curve graph look like?

Steep curve in the beginning, becoming less steep, eventually flattening out when the reaction stops.

What four factors can you alter to change the rate of a reaction?

Surface area, temperature, concentration (and pressure), add a catalyst