Collision Theory Factors affecting rate Investigate how concentration 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 Collisions & Activation Energy Next slide Factors affecting Rate of reaction 1. Concentration 2. Temperature 3. Particle size 4. Nature of reactants 5. Presence of a catalyst Effect of concentration on rate Increasing concentration increases the rate By increasing the number of collisions Investigate the effect of concentration on reaction rate HCl + Na2S2O3 NaCl + SO2 + H2O + S The formation of a pale yellow precipitate of sulphur can be used to monitor the progress of the reaction To investigate the effect of concentration on reaction rate Next slide Add the HCl to the Na2S2O3 in the flask Record the time taken for the X to disappear Repeat with different concentrations of Na2S2O3 Inverse the time to get the rate Effect of concentration on rate Conclusion ? R A T E 1 Time Rate is directly proportional to concentration CONCENTRATION 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 + H 2O + 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 Collision Theory Factors affecting rate Investigate how temperature 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 Temperature, Collisions & Activation Energy Next slide Effect of temperature on rate Increasing temperature increases the rate By increasing the number of collisions / sec More of the colliding particles have E Act Investigate the effect of temperature on reaction rate HCl + Na2S2O3 NaCl + SO2 + H2O + S The formation of a pale yellow precipitate of sulphur can be used to monitor the progress of the reaction To investigate the effect of temperature on reaction rate Next slide Add the HCl to the Na2S2O3 in the flask Record the temperature after mixing Record the time taken for the X to disappear Inverse the time to get the rate Repeat at different temperatures Next slide Effect of temperature on rate Conclusion ? R A T E 1 Rate increases with increasing temperature Time TEMPERATURE Effect of temperature on rate What is the main factor increasing rate between A and B R A T E 1 Time B A TEMPERATURE Rate increases due to increased collisions /sec Effect of temperature on rate R A T E C What other factor caused the large rate increase between B and C 1 Time B TEMPERATURE More colliding particles have E Act Nature of reactants affect the 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 Nature of reactants affects rate Ionic reactions are fast + Na Cl + Ag+NO 3 = Ag+Cl + Na+NO 3 Mix solutions of sodium chloride and silver nitrate A precipitate of silver chloride forms instantly Ions are free to move in solution....no bonds to break Sodium chloride + Silver Nitrate next Covalent reactions are slower than ionic HCl + Na2S2O3 NaCl + SO2 + H2O + S The pale yellow precipitate of sulphur forms slowly as covalent bonds in the sodium thiosulfate must first be broken before the reaction can occur End