1. Collision Theory Factors affecting rate Particle size affects rate

2. Collision Theory 1.For a reaction to occur the particles must collide 2.The colliding particles must have a minimum energy called the Activation Energy

3. Factors affecting Rate of reaction 1.Concentration 2. Temperature 3.Particle size 4.Nature of reactants 5.Presence of a catalyst

4. Effect of Particle size on rate Smaller particles have a greater surface area Next slide

5. Surface area, collisions & rate Next slide

6. The rate of release of CO 2 gas can be used to monitor the progress of the reaction HClCaCO 3 H2OH2O+ Investigate the effect of particle size on reaction rate ++ CO 2 CaCl 2

7. Add the HCl to a large chips of CaCO 3 in the flask As CO2 is released the mass of the flask drops Next slide

8. Record the time taken for the release of CO 2 to end ( No further mass loss) Repeat using the same mass of powdered CaCO 3 and the same volume of HCl And the same concentration of HCL

9. Result Finely divided particles react faster than large particles