Collision Theory Factors affecting rate Particle size affects rate

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

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

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

Surface area, collisions & rate Next slide

Investigate the effect of particle size on reaction rate HCl + CaCO3 CaCl2 + H2O + CO2 The rate of release of CO2 gas can be used to monitor the progress of the reaction

Add the HCl to a large chips of CaCO3 in the flask As CO2 is released the mass of the flask drops Next slide

Record the time taken for the release of CO2 to end ( No further mass loss) Repeat using the same mass of powdered CaCO3 and the same volume of HCl And the same concentration of HCL

Result Finely divided particles react faster than large particles