chemical kinetics
DESCRIPTION
This set of powerpoint slides revolves around the topic of chemical kinetics. Are you looking for notes on factors affecting speed of reaction? Looking for foolproof ways to calculate the rate of reaction? You have come to the right place! Excellent as a chemistry study material and as an examination revision tool :) A short and sweet O level topic guide with the things you need to ace in chemical kinetics!TRANSCRIPT
Chemical kinetics
Rate of a reaction O 1) amount of reactant used up/time
taken O 2) amount of product formed/time
takenO 3) volume of gas produced/time
taken
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.
Experimentation Time! O Conduct your own experiment and
sketch out your own vol. of hydrogen vs time graph!
Graph analysisO Gradient of graph speed of
reactionO 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
Measuring speed of reaction-changes in massO Allow gas produced to escape and
measure the loss of massO Reaction speed determined by
measuring loss of mass at regular time intervals
Factors affecting rate of a chemical reaction
O Summary: O Temperature O Concentration O PressureO Surface area O Presence of a catalyst
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
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
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)
O Answer: O The low temperature slows down
chemical reactions which makes the food turn bad.
Factor 2: Concentration/Pressure O High concentration/pressure more
particles per unit volume increase in frequency of collisions rate of reaction increases
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
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?
The end Learn through understanding,
not through memorization.