Chemical kinetics
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Transcript of Chemical kinetics
![Page 1: Chemical kinetics](https://reader035.fdocuments.net/reader035/viewer/2022062405/5550400eb4c9058f768b4958/html5/thumbnails/1.jpg)
Chemical kinetics
![Page 2: Chemical kinetics](https://reader035.fdocuments.net/reader035/viewer/2022062405/5550400eb4c9058f768b4958/html5/thumbnails/2.jpg)
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
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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.
![Page 4: Chemical kinetics](https://reader035.fdocuments.net/reader035/viewer/2022062405/5550400eb4c9058f768b4958/html5/thumbnails/4.jpg)
Experimentation Time! O Conduct your own experiment and
sketch out your own vol. of hydrogen vs time graph!
![Page 5: Chemical kinetics](https://reader035.fdocuments.net/reader035/viewer/2022062405/5550400eb4c9058f768b4958/html5/thumbnails/5.jpg)
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
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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
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Factors affecting rate of a chemical reaction
O Summary: O Temperature O Concentration O PressureO Surface area O Presence of a catalyst
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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
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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
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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)
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O Answer: O The low temperature slows down
chemical reactions which makes the food turn bad.
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Factor 2: Concentration/Pressure O High concentration/pressure more
particles per unit volume increase in frequency of collisions rate of reaction increases
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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
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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?
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The end Learn through understanding,
not through memorization.