Rates of reaction
 Chemical reactions take place at very different rates –
some are very fast (like explosions) and other...
Experiment 1 – using a measuring
cylinder.
 In this experiment the reagents are calcium carbonate
(limestone) and citric ...
Measure volume
on a measuring
cylinder
Results Rate of reaction experiment
Time (s) Volume of Carbon Dioxide (ml)
0 0
30 16
60 25
90 31
120 34
150 35
180 36
210 ...
Measuring rates We can record the rate using this relation|:
 Rate of reaction = change in recorded property
time for th...
GRAPH OF RESULTS
0
5
10
15
20
25
30
35
40
0 50 100 150 200 250 300
Volumeofhyrdoger
Time (s)
Rate of reaction experiment.
...
GRAPH OF RESULTS
0
5
10
15
20
25
30
35
40
0 50 100 150 200 250 300
Volumeofcarbondioxide
Time (s)
Rate of reaction experim...
GRAPH OF RESULTS
0
5
10
15
20
25
30
35
40
0 50 100 150 200 250 300
Volumeofcarbondioxide
Time (s)
Rate of reaction experim...
Calculation
 Calculate the number of moles of carbon dioxide
produce in experiment 1 above.
 Volume of carbon dioxide = ...
Experiment 2
 In this experiment calcium carbonate reacts with
ethanioc acid (acetic acid).
 The rate of reaction is mea...
Experiment 3
 In this experiment calcium carbonate reacts with citric
acid.
 The rate of reaction is measured the mass o...
Factors affecting reaction rates
 Concentration
 The higher the level of concentration (or pressure in
gases) the faster...
Factors affecting reaction rates
 Surface area in solids
 The larger the surface area of a solid the faster the
reaction...
Factors affecting reaction rates
 Temperature
 The higher the temperature the faster the reaction.
 This is due to incr...
Maxwell Boltzman distribution
Temperature effect
Temperature effects explained Only molecules with enough activation energy will
react to form the products.
Factors affecting reaction rates
 Catalysts
 Catalysts increase the rates of chemical reactions.
 This is due a lowerin...
Catalyst effect
Catalyst effect
Collision theory
 Scientists assume all gases are made of particles in
constant random motion. They have regular elastic
...
Links to factors affecting rate of reaction when limestone reacts
with de-scaling acids.
 http://ie.dynapipe.co.uk/how-to...
Rate of reaction for limestone  citric acid reaction.
Rate of reaction for limestone  citric acid reaction.
Rate of reaction for limestone  citric acid reaction.
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Rate of reaction for limestone citric acid reaction.

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Rate of reaction - citric acid and limestone

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Rate of reaction for limestone citric acid reaction.

  1. 1. Rates of reaction  Chemical reactions take place at very different rates – some are very fast (like explosions) and others may take months or years to proceed.  In a chemical reaction which produces a gas the rate can be measured by determining the volume of gas produced as time passes.  Limestone produces carbon dioxide gas when it reacts with an acid. The rate of production of carbon dioxide can be measured in several ways.
  2. 2. Experiment 1 – using a measuring cylinder.  In this experiment the reagents are calcium carbonate (limestone) and citric acid.  The products are calcium citrate, carbon dioxide gas and water.  The rate of the reaction is measured by measuring how fast the carbon dioxide gas is produced.  The limiting reagent is the amount of citric acid. This is the first reagent to be use up.
  3. 3. Measure volume on a measuring cylinder
  4. 4. Results Rate of reaction experiment Time (s) Volume of Carbon Dioxide (ml) 0 0 30 16 60 25 90 31 120 34 150 35 180 36 210 36 240 36
  5. 5. Measuring rates We can record the rate using this relation|:  Rate of reaction = change in recorded property time for the change  Actual rate is the gradient of the line of the product concentration versus time graph.  Average rate is the gradient of the line joining the two point in time over which the rate is being measured.
  6. 6. GRAPH OF RESULTS 0 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 Volumeofhyrdoger Time (s) Rate of reaction experiment. Rapid reaction here Reaction slows down here. Reaction stops here
  7. 7. GRAPH OF RESULTS 0 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 Volumeofcarbondioxide Time (s) Rate of reaction experiment. Rate of reaction experiment Volume of Hydrogen (ml) Rate at the start of the reaction.
  8. 8. GRAPH OF RESULTS 0 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 Volumeofcarbondioxide Time (s) Rate of reaction experiment. Rate of reaction experiment Volume of Hydrogen (ml) Average rate of reaction between 0s and 200s.
  9. 9. Calculation  Calculate the number of moles of carbon dioxide produce in experiment 1 above.  Volume of carbon dioxide = 36ml  1 mole of carbon dioxide = 24000 ml  Number of moles of carbon dioxide  = 36 ÷ 24000  = 0.0015 moles
  10. 10. Experiment 2  In this experiment calcium carbonate reacts with ethanioc acid (acetic acid).  The rate of reaction is measured by collecting the carbon dioxide gas produced in a gas syringe.  The results can be processed in the same way as those for experiment 1. Best method
  11. 11. Experiment 3  In this experiment calcium carbonate reacts with citric acid.  The rate of reaction is measured the mass of the remaining chemicals.  The loss in mass is due to the escaping carbon dioxide gas.  The results can be processed in the same way as those for experiment 1 except that the factor changing is the mass and not the volume.
  12. 12. Factors affecting reaction rates  Concentration  The higher the level of concentration (or pressure in gases) the faster the reaction.  This is due to increased collisions between reacting particles.
  13. 13. Factors affecting reaction rates  Surface area in solids  The larger the surface area of a solid the faster the reaction. Finely divided substances have much larger surface areas than large chunks of a solid.  This is due to increased collisions between reacting particles.
  14. 14. Factors affecting reaction rates  Temperature  The higher the temperature the faster the reaction.  This is due to increased and more energetic collisions between reacting particles.  A 10oC rise in temperature often results in a doubling of the reaction rate.
  15. 15. Maxwell Boltzman distribution
  16. 16. Temperature effect
  17. 17. Temperature effects explained Only molecules with enough activation energy will react to form the products.
  18. 18. Factors affecting reaction rates  Catalysts  Catalysts increase the rates of chemical reactions.  This is due a lowering of the activation energy for the reaction.  Catalysts are not consumed in the reaction so in theory they can be used over and over again. In practice they are often contaminated and/or some is lost in a process.
  19. 19. Catalyst effect
  20. 20. Catalyst effect
  21. 21. Collision theory  Scientists assume all gases are made of particles in constant random motion. They have regular elastic collisions with other molecules.  Gas molecules collide with the walls of their container and exert pressure but do not lose energy in their collisions and do not attract other molecules.  The volume of actual gas molecules in a container is negligible and their average kinetic energy is proportional to the temperate (Kelvin).
  22. 22. Links to factors affecting rate of reaction when limestone reacts with de-scaling acids.  http://ie.dynapipe.co.uk/how-to-remove-limescale.htm  http://en.wikipedia.org/wiki/Limescale  http://www.movia.ro/decalcifiere_eng.html  http://www.thor.com/view.asp?id=20130408120303AAmFq15  http://www.newworldencyclopedia.org/entry/acetic_acid  http://www.newworldencyclopedia.org/entry/Citric_acid  http://en.wikipedia.org/wiki/Sulfamic_acid  http://www.lihuasz.com/news/what_is_sulfamic_acif-en.html  http://www.yangheng.com/zycp08.htm  http://uk.answers.yahoo.com/question/index?qid=20130414114029AATzCWd  http://www.howtocleanthings.com/appliances/how-to-clean-coffee-maker.htm  http://chowhound.chow.com/topics/360882  http://scottiestech.info/2009/04/22/descaling-appliances-which-acid-is-best/  http://www.ceragol.com/en/products/premium-descaler/descaling/  http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Acetic_acid.html  http://en.wikipedia.org/wiki/Calcium_carbonate  http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Calcium_carbonate.html

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