The document discusses chemical kinetics, focusing on how to measure the rate of a reaction through methods such as gas volume, mass changes, and graph analysis. It highlights factors affecting reaction rates, including temperature, concentration, pressure, surface area, and the presence of catalysts, explaining the collision theory that underpins these processes. It encourages experimentation and comprehension rather than mere memorization of concepts.

1. Chemical kinetics

2. Rate of a reaction
O 1) amount of reactant used up/time taken
O 2) amount of product formed/time taken
O 3) volume of gas produced/time taken

3. Measuring rate of reaction –
volume of gas produced
O Since magnesium reacts with dilute HCl to
form hydrogen gas, the speed of reaction
can hence be determined by measuring
the volume of hydrogen gas produced at
regular time intervals.

4. Experimentation Time!
O Conduct your own experiment and sketch
out your own vol. of hydrogen vs time
graph!

5. Graph analysis
O Gradient of graph  speed of reaction
O The steeper the gradient, the faster the
speed of reaction
O Decrease in steepness indicates
decreasing speed of reaction
O Shape of graph  changes/consistency in
speed of reaction as time passes

6. Measuring speed of reactionchanges in mass
O Allow gas produced to escape and
measure the loss of mass
O Reaction speed determined by measuring
loss of mass at regular time intervals

7. Factors affecting rate of a
chemical reaction
O Summary:
O Temperature
O Concentration
O Pressure
O Surface area
O Presence of a catalyst

8. Collision theory
O For a reaction to occur, reacting particles
must
O 1) collide with each other
O 2) possess activation energy
O Note: Orientation of collision must be
correct as well

9. Factor 1: Temperature
O Increase in temp.  increase in KE 
increase in no. of collisions + increase in
no. of particles with greater than required
amount of activation energy  more
particles react  increase rate of reaction

10. Put on your thinking cap!
O Can you explain why food should be kept
in deep-freeze compartments in order to
ensure its freshness?
O (answer on next slide)

11. O Answer:
O The low temperature slows down
chemical reactions which makes the food
turn bad.

12. Factor 2:
Concentration/Pressure
O High concentration/pressure  more
particles per unit volume  increase in
frequency of collisions  rate of reaction
increases

13. Factor 3: Surface area
O Increase in surface area/particle size 
increase in exposure to the other reactant
 increase in probability of collisions 
increase in rate of reaction

14. Factor 4: Presence of Catalyst
O Speeds up rate of reaction through
lowering activation energy needed for
reaction to occur
O Think: What can you infer from the above
statement?

15. The end
Learn through understanding, not
through memorization.