Topic 9

Question 1

Collision theory

Answer 1

Particles must collide to react

Question 2

Reactions won’t take place unless

Answer 2

The collision is in the right direction

The particles collide with at least a certain minimum amount of kinetic energy (activation energy)

Question 3

activation energy

Answer 3

The minimum amount of energy required for a reaction to take place

Question 4

Reaction rate define it

Answer 4

The change in amount of reactant or product per unit of time

Question 5

Rate of reaction =

Answer 5

Amount of reactant used or amount of product formed over time taken

Question 6

Catalysts increase rate of reaction by…

Answer 6

Providing an alternative reaction pathway with a lower activation energy so great proportion of collisions result in a reaction. The catalyst is chemically unchanged at the end of the reaction

Question 7

Heterogeneous catalysts

Answer 7

Catalysts in a different state to the reactant

Question 8

Solid catalysts can provide a surface for the reaction to take place on

Answer 8

Reactant molecules arrive at the surface and bond with the solid catalyst this is known as adsorption
The bond between the reactant’s atoms are weekend and break up. This forms radicals. These radicals get together and make new molecules
The new molecules ore then detached from the catalyst this is known as desorption

Question 9

Homogeneous catalysts

Answer 9

Same physical state as the reactants
The reactants combine with the catalyst to make an intermediate species which then reacts to form the products and reforms the catalyst