Collision theory

A collision

No

As there is a minimum energy needed

The activation energy. Symbol - E_A

As concentration increases, the total number of collisions increases, causing more successful collisions, so the reaction rate increases

As the particle size gets smaller, then surface area gets bigger. This allows more total collisions to take place between reacting particles, making more sucessful collision and hence increasing the reaction rate

• As the temperature increases, the particles move faster. This allows more total collisions to take place between reacting particles, making more successful collisions and hence increasing the reaction rate.
• Also, because temperature is a measure of the average kinetic energy of the particles, when particles are heated the collisions between them are of higher energy. Therefore more of them are equal to or greater than the activation energy resulting in more successful collisions and making the reaction rate increase.

doubles

They speed up a chemical reaction and are recovered chemically unchanged at the end of a reaction

• Heterogeneous - the catalyst is in a different state from the reactants
• Homogeneous - the catalyst in in the same state as the reactants

By lowering the activation energy for the reaction

When impurities present in the reactants adsorb onto the surface of the catalyst taking up 'sites' which could otherwise have been occupied by reactant particles

Biological catalysts

Fermentation

To catalyse the conversion of poisonous carbon monoxide and oxides of nitrogen into carbon dioxide and nitrogen

• Platinum
• Palladium
• Rhodium

Since lead poisons the platinum metal which is used as the catalyst