3b

• Increases the rate of reaction by providing an alternative pathway with lower activation energy. • Chemically unchanged at the end of the reaction.

• Surface area • Temperature • Concentration/Pressure • Catalyst

A measure of how quickly a reactant is used up or a product is formed

• Reactant particles must collide with each other (Affected by concentration/pressure or surface area) • The particles must have enough energy for them to react (affected by temperature or catalyst)

Increasing concentration in solution or pressure in gases increases the rate of reaction: - Particles are close together - Collision frequency increases - More chances of a successful collision

Increasing temperature increases rate of reaction: - Particles have more energy and move quicker - Collision frequency with energy needed increases - More chances of a successful collision

Increasing surface are increases rate of reaction (Powders have a higher surface are than lumps): - More area exposed, there are more places for collision to occur - Collision frequency increases - More chances of a successful collision