Chemistry C2 GCSE AQA - Unit 4

Follow up to units 1, 2 and 3

HideShow resource information

How Fast?

  • Rate= amount of reactant used / time
  • OR
  • Amound of product formed / time
  • This equals the RATE OF REACTION
1 of 5

Collision Theory

  • States reactions only happen if particles COLLIDE
  • The particles must collide with enough ENERGY to change into NEW SUBSTANCES
  • Minimum energy needed is called the ACTIVATION ENERGY
  • Factors that increase this are
    • TEMPERATURE
    • CONCENTRATION / PRESSURE
    • SURFACE AREA of solids
    • Use of a CATALYST
2 of 5

Effect of Temperature

(http://i48.tinypic.com/2u5tipy.png)

3 of 5

Effect of Concentration

(http://i45.tinypic.com/33e55k6.png)

4 of 5

Effect of a Catalyst

  • Catalysts change the rates of chemical reactions
  • Most used to SPEED UP reactions
  • Catalyst is left at the end of the reaction so it can be REUSED
  • Work by LOWERING the ACTIVATION ENERGY
    • Means MORE collisions in a reaction
  • Most expensive, but ECONOMICAL - they do not need replacing often
5 of 5

Comments

Nuha

this is good :)

Jemima

thanks :D 

OneTooManyAnOpinion

Jemima wrote:

thanks :D 

No problem :)

OneTooManyAnOpinion

Nuha wrote:

this is good :)

 Thank you! :)

Similar Chemistry resources:

See all Chemistry resources »See all resources »