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Collision Theory Factors affecting rate Investigate how concentration affects rate
| Date post: | 11-May-2015 |
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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
The formation of a pale yellow precipitate of sulphur can be used to monitor the progress of
the reaction
HCl Na2S2O3 H2O+NaCl
Investigate the effect of concentration on reaction rate
+ + S+ SO2
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
RATE
CONCENTRATION
Conclusion ?
Rate is directly proportional to concentration
1
Time
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
The rate of release of CO2 gas can be used to monitor the progress of the reaction
HCl CaCO3 H2O +
Investigate the effect of particle size on reaction rate
+ + CO2CaCl2
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
The formation of a pale yellow precipitate of sulphur can be used to monitor the progress of
the reaction
HCl Na2S2O3 H2O+NaCl
Investigate the effect of temperature on reaction rate
+ + S+ SO2
To investigate the effect of temperature on reaction rate
Next slide
Add the HCl to the Na2S2O3 in the flask
Record the time taken for the X to disappear
Record the temperature after mixing
Inverse the time to get the rate
Next slide
Repeat at different temperatures
Effect of temperature on rate
RATE
TEMPERATURE
Conclusion ?
Rate increases with increasing temperature
1
Time
Effect of temperature on rate
RATE
TEMPERATURE
What is the main factor
increasing rate between A and B
Rate increases due to increased collisions /sec
1
Time
A
B
Effect of temperature on rate
RATE
TEMPERATURE
What other factor caused the large rate
increase between B and C
More colliding particles have E Act
1
Time
C
B
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+NO3-+ =
Ag+Cl-+
Na+NO3-
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
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The pale yellow precipitate of sulphur forms slowly as covalent bonds in the sodium thiosulfate must first
be broken before the reaction can occur
HCl Na2S2O3 H2O+NaCl+ + S+ SO2
Covalent reactions are slower than ionic
End
