Rate of Reaction

how does surface area affect rate of reaction?

• increase in surface area increases rate of reaction

• more of reactant is exposed

• more frequent collisions

• more successful collisions per unit time

how does concentration affect rate of reaction?

• increasing concentration increases rate of reaction

• more particles in the same volume

• more frequent collisions

• more successful collisions per unit time

how does pressure affect rate of reaction?

• increasing pressure increases rate of reaction

• same number of particles in a smaller volume

• more frequent collisions

• more successful collisions per unit time

how does temperature affect rate of reaction?

• increasing temperature increases rate of reaction

• particles have more kinetic energy

• more particles collide with the required activation energy

• more successful collisions per unit time

how does catalyst affect rate of reaction?

• provides an alternative pathway

• with a slower activation energy

• more successful collisions per unit time

• rate of reaction increases

explain how you would be able to re-use the same catalyst later on

as it increases rate without getting used up

name two catalysts

manganese (IV) oxide

lead (IV) oxide

2H₂O₂ →

O₂ + 2H₂O

what is the relationship between rate and concentration?

rate is directly proportional to concentration

is rate proportional to temperature?

no

how would you prove the catalyst didn’t get used up in the experiment?

• add x grams of catalyst to reaction

• filter off catalyst at end

• allow to dry

• re-weigh catalyst

• should still have x grams

why does rate decrease during a reaction?

• the reactant gets used up

  • SA/concentration of reactant decreases

  • less frequent collisions

  • less successful collisions per unit time

  • eventually reaction stops when one reactant is used up

what is the purpose of the cotton wool?

allows gas to escape but prevents liquid escaping

what is going to happen to the reading on the balance during the reaction? Explain.

decrease, as CO₂ is produced and escapes through cotton wool

why is this method not that accurate?

• hard to read measuring cylinder

• CO₂ will dissolve in water so lower than expected volume collected

what is a more accurate piece of equipment than using the water measuring cylinder method to collect gas?

gas syringe

what is the test for oxygen?

• put glowing splint in the gas

• if relights, oxygen in produced

why is this method more accurate than the water cylinder method?

easier to read scale and no gas can dissolve in water

what is the biggest issue with accuracy in this experiment?

human judgement required

suggest a reason why the volume of gas collected is less than the expected value

gas escaped before bung was put on so reaction started before bung was put on