temperature and the rate of reaction l.o: to understand the effect of temperature on the rate of a...
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Temperature and the Temperature and the Rate of ReactionRate of Reaction
L.O: To understand the L.O: To understand the effect of temperature on effect of temperature on
the rate of a reactionthe rate of a reaction
The rate tells us how fast the reactants The rate tells us how fast the reactants are turned into products in a chemical are turned into products in a chemical reaction.reaction.
Why do you think this happens? Why do you think this happens? Come up with a theory Come up with a theory
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How does temperature affect rate?Lets see if the same thing happens to other chemicals!The reaction between sodium thiosulfate and hydrochloric acid produces sulfur.
Sulfur is solid and so it turns the solution cloudy.
How can this fact be used to measure the effect of temperature on rate of reaction?
hydrochloricacid
sodiumchloride
sulfursodium
thiosulfate + + watersulfur
dioxide ++Na2S2O3
(aq)2HCl(aq)
2NaCl(aq)
S(s)++
SO2
(g)H2O(l)
+ +
Sodium thiosulphate + hydrochloric acid Sodium thiosulphate + hydrochloric acid → sodium chloride + sulphur → sodium chloride + sulphur dioxide + sulphur + waterdioxide + sulphur + water
1.1. Take the cold bottle of sodium thiosulfate Take the cold bottle of sodium thiosulfate out of ice..out of ice..
2.2. Record the temperature of the sodium Record the temperature of the sodium thioslphate in your table. thioslphate in your table.
3.3. Measure 5cmMeasure 5cm33 of acid. of acid.4.4. Add the acid to the bottle and lay it on the Add the acid to the bottle and lay it on the
cross in the petri dish, start the clock.cross in the petri dish, start the clock.5.5. Look down through the flask Time how Look down through the flask Time how
long it takes until the cross disappears, long it takes until the cross disappears, record this in your results table.record this in your results table.
6.6. Repeat the experiment with different Repeat the experiment with different temperatures sodium thiosulphate.temperatures sodium thiosulphate.
Look down here
Temperature Temperature °C°C
Time for cross Time for cross to disappearto disappear
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The effect of temperature on rate
Draw a sketch graph of your resultsDraw a sketch graph of your results
TempTemp
((ooC)C)
Time takenTime taken
(s)(s)
2525 100100
3030 6060
3535 4040
4040 2525
4545 1515
50 50 1010
Time vs Temperature graphs
0
20
40
60
80
100
120
20 30 40 50 60
Time(s) vs Temp(oC)T
ime
Temp
Reaction takes a long time here
Reaction is quicker here
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Rates of reaction
Why are some reactions faster than others?
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Reactions, particles and collisions
Reactions take place when particles collide with a certain amount of energy.
The minimum amount of energy needed for the particles to react is called the activation energy, and is different for each reaction.
The rate of a reaction depends on two things:
the frequency of collisions between particles
the energy with which particles collide.
If particles collide with less energy than the activation energy, they will not react. The particles will just bounce off each other.
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Temperature and collisions
How does temperature affect the rate of particle collision?
How do the particles differ in these How do the particles differ in these substances?substances?
particle diagramsparticle diagrams Particles collide more oftenParticles collide more often Particles collide with more energyParticles collide with more energy
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Effect of temperature on rate
The higher the temperature, the faster the rate of a reaction. In many reactions, a rise in temperature of 10 °C causes the rate of reaction to approximately double.
Why does increased temperature increase the rate of reaction?
At a higher temperature, particles have more energy. This means they move faster and are more likely to collide with other particles.
When the particles collide, they do so with more energy, and so the number of successful collisions increases.
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Temperature and particle collisions
2HCl + Na2HCl + Na22SS22OO33 →→ 2NaCl + SO 2NaCl + SO22 + S + H + S + H22OO
Conclusion:Conclusion:
Are the class results reproducible?Are the class results reproducible?
Why?Why?
What were the errors?What were the errors?
How could you reduce the errors?How could you reduce the errors?
Rates of reactionHow to improve your experiment
Click on linkhttp://espresso/espresso/clipbank/
servlet/link?macro=setresource&template=vid&reso
urceID=1684
Watch the video. Use the information to describe how
you can improve your sodium thiosulphate and acid
experiment.
The assessed bit!The assessed bit!
(4 marks)(4 marks)
Explain why rate of reaction is faster at higher temperatures in terms of collisions
19/04/2319/04/23
Rate of reaction graph v2Rate of reaction graph v2Amount of product formed/ amount of reactant used up
Time
Slower reaction Low Temp
Fast rate of reaction here
High temp
Slower rate of reaction here due to reactants being used up
Rate of reaction = amount of product formed/reactant used up
time
Acid and marbleAcid and marble