KINETICS
Collision theory
● Reactant particles must collide with correct orientation
● Reactant particles must collide with sufficient energy to overcome the
activation energy
Activation energy
● Minimum amount of energy needed for particles to collide in order for
a chemical reaction to occur
Rate of a reaction
● Rate of change in concentration of reactants of products per unit time
● Unit = mol . dm-3 . s-1
Change of [Reactants]
1. Fast rate → Many particles = many collision so a steep rate
2. Reaction slows down → [Reactants] is decreasing due to increasing
collisions
3. Reaction has stopped
Change of [Products]
1. Fast rate → Many particles = many collisions
2. Reaction slows down → Less [Reactants] so less collisions
3. Reactions has stopped due to no more collisions
, Ways of measuring the rate of reaction
Change in volume of gas products
● Volume of gas products/ concentration of gas products is plotted
against time
● Gas syringe is used in the experiment
Change in mass
● Does not work with hydrogen gas because it is too light
● Graph can be plotted = continuous readings
Change in concentration via titration
● Continuous data
● Samples taken from reaction at different time intervals (analyzed via
titration)
Formation of a precipitate
● Non continuous method (clock reactions)
● Observable method
● Data is obtained as an average rate (time taken for reaction to
produce x)
Change in color intensity
● Colorimeter/spectrophotometer is used to shine light in chemical
reaction
● 1 reactant/particles has to be colored
● Passing light of a specific wavelength and measuring the light
intensity + light transmission
Collision theory
● Reactant particles must collide with correct orientation
● Reactant particles must collide with sufficient energy to overcome the
activation energy
Activation energy
● Minimum amount of energy needed for particles to collide in order for
a chemical reaction to occur
Rate of a reaction
● Rate of change in concentration of reactants of products per unit time
● Unit = mol . dm-3 . s-1
Change of [Reactants]
1. Fast rate → Many particles = many collision so a steep rate
2. Reaction slows down → [Reactants] is decreasing due to increasing
collisions
3. Reaction has stopped
Change of [Products]
1. Fast rate → Many particles = many collisions
2. Reaction slows down → Less [Reactants] so less collisions
3. Reactions has stopped due to no more collisions
, Ways of measuring the rate of reaction
Change in volume of gas products
● Volume of gas products/ concentration of gas products is plotted
against time
● Gas syringe is used in the experiment
Change in mass
● Does not work with hydrogen gas because it is too light
● Graph can be plotted = continuous readings
Change in concentration via titration
● Continuous data
● Samples taken from reaction at different time intervals (analyzed via
titration)
Formation of a precipitate
● Non continuous method (clock reactions)
● Observable method
● Data is obtained as an average rate (time taken for reaction to
produce x)
Change in color intensity
● Colorimeter/spectrophotometer is used to shine light in chemical
reaction
● 1 reactant/particles has to be colored
● Passing light of a specific wavelength and measuring the light
intensity + light transmission
