1 / 64

iGCSE chemistry Section 4 lesson 3

iGCSE chemistry Section 4 lesson 3. Content. The iGCSE Chemistry course. Section 1 Principles of Chemistry Section 2 Chemistry of the Elements Section 3 Organic Chemistry Section 4 Physical Chemistry Section 5 Chemistry in Society. Content. Section 4 Physical Chemistry.

plori
Télécharger la présentation

iGCSE chemistry Section 4 lesson 3

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. iGCSE chemistrySection 4 lesson 3

  2. Content The iGCSE Chemistry course Section 1 Principles of Chemistry Section 2 Chemistry of the Elements Section 3 Organic Chemistry Section 4 Physical Chemistry Section 5 Chemistry in Society

  3. Content Section 4 Physical Chemistry • Acids, alkalis and salts • Energetics • Rates of reaction • Equilibria

  4. Lesson 3 c) Rates of reaction c) Rates of reaction 4.17 describe experiments to investigate the effects of changes in surface area of a solid, concentration of solutions, temperature and the use of a catalyst on the rate of a reaction 4.18 describe the effects of changes in surface area of a solid, concentration of solutions, pressure of gases, temperature and the use of a catalyst on the rate of a reaction 4.19 understand the term activation energy and represent it on a reaction profile 4.20 explain the effects of changes in surface area of a solid, concentration of solutions, pressure of gases and temperature on the rate of a reaction in terms of particle collision theory 4.21 explain that a catalyst speeds up a reaction by providing an alternative pathway with lower activation energy.

  5. Rates of Reaction The rate of reaction is the rate at which products are formed, or the rate at which reactions are used up, in a reaction.

  6. Rates of Reaction Chemical reactions will only occur when the reacting particles collide with each other with sufficient energy so they react.

  7. Rates of Reaction Chemical reactions will only occur when the reacting particles collide with each other with sufficient energy so they react. The ACTIVATION ENERGY is the minimum amount of energy required to cause the reaction to happen.

  8. Rates of Reaction Chemical reactions will only occur when the reacting particles collide with each other with sufficient energy so they react. The ACTIVATION ENERGY is the minimum amount of energy required to cause the reaction to happen. There are FIVE very important factors which can affect the rate of reaction.

  9. Rates of Reaction

  10. Rates of Reaction

  11. Rates of Reaction

  12. Rates of Reaction

  13. Rates of Reaction

  14. Rates of Reaction Let’s not forget here a little dose of kinetic theory

  15. Rates of Reaction Let’s not forget here a little dose of kinetic theory Kinetic what?

  16. Rates of Reaction Kinetic theory is all about the random movement of particles

  17. Rates of Reaction Kinetic theory is all about the random movement of particles

  18. Rates of Reaction Kinetic theory assumes that particles are in constant random motion Kinetic theory is all about the random movement of particles

  19. Rates of Reaction Kinetic theory assumes that particles are in constant random motion Kinetic theory is all about the random movement of particles ! And there will be collisions!

  20. Rates of Reaction Kinetic theory assumes that particles are in constant random motion Kinetic theory is all about the random movement of particles ! And there will be collisions! It’s these collisions that are the cause of chemical reactions.

  21. Rates of Reaction Do you remember the five factors that can affect the rate of chemical reactions?

  22. Rates of Reaction

  23. Rates of Reaction Let’s now consider each one of these factors in turn

  24. Rates of Reaction 1. Temperature of the Reactants

  25. Rates of Reaction 1. Temperature of the Reactants Low temperature Cold conditions, particles have little energy, move slowly and collide infrequently and less successfully

  26. Rates of Reaction 1. Temperature of the Reactants Low temperature High temperature HEAT Cold conditions, particles have little energy, move slowly and collide infrequently and less successfully When heated, particles have more energy, move faster, collide frequently and more successfully

  27. Rates of Reaction 1. Temperature of the Reactants Low temperature High temperature Raising the temperature = particles move faster and collide frequently, collisions are successful and so the rate of reaction increases! HEAT Cold conditions, particles have little energy, move slowly and collide infrequently and less successfully When heated, particles have more energy, move faster, collide frequently and more successfully

  28. Rates of Reaction 2. Concentration of the Dissolved Reactants

  29. Rates of Reaction 2. Concentration of the Dissolved Reactants Low concentration Particles are spread out and will collide with each other less often, with fewer successful collisions

  30. Rates of Reaction 2. Concentration of the Dissolved Reactants Low concentration High concentration Particles are spread out and will collide with each other less often, with fewer successful collisions Particles are crowded close together, so collide more often, with more successful collisions

  31. Rates of Reaction 2. Concentration of the Dissolved Reactants Low concentration High concentration Increasing the concentration = particles are more crowded together and collide frequently, collisions are successful and so the rate of reaction increases! Particles are spread out and will collide with each other less often, with fewer successful collisions Particles are crowded close together, so collide more often, with more successful collisions

  32. Rates of Reaction 3. Pressure (in gases)

  33. Rates of Reaction 3. Pressure (in gases) Low pressure Particles are spread out and will collide with each other less often, with fewer successful collisions

  34. Rates of Reaction 3. Pressure (in gases) Low pressure High pressure Particles are spread out and will collide with each other less often, with fewer successful collisions Particles are pushed closer together, they collide more frequently, with more successful collisions

  35. Rates of Reaction 3. Pressure (in gases) Low pressure High pressure Increasing the pressure = particles in a gas are pushed closer together and collide frequently, collisions are successful and so the rate of reaction increases! Particles are spread out and will collide with each other less often, with fewer successful collisions Particles are pushed closer together, they collide more frequently, with more successful collisions

  36. Rates of Reaction 4. Surface area of solid reactants

  37. Rates of Reaction 4. Surface area of solid reactants Small surface area Large particles have a small surface area in relation to volume – less particles exposed, fewer collisions, slow reaction

  38. Rates of Reaction 4. Surface area of solid reactants Large surface area Small surface area Large particles have a small surface area in relation to volume – less particles exposed, fewer collisions, slow reaction Smaller particles have a larger surface area in relation to volume- more particles exposed, more collisions, faster reaction

  39. Rates of Reaction 4. Surface area of solid reactants Large surface area Small surface area Reducing the particle size and so increasing the relative surface area means that there are more successful collisions and a faster rate of reaction. Large particles have a small surface area in relation to volume – less particles exposed, fewer collisions, slow reaction Smaller particles have a larger surface area in relation to volume- more particles exposed, more collisions, faster reaction

  40. Rates of Reaction 5. Using a catalyst

  41. Rates of Reaction 5. Using a catalyst A catalyst is a substance which increases the rate of a chemical reaction without being used up itself. It can be used over and over again.

  42. Rates of Reaction 5. Using a catalyst A catalyst is a substance which increases the rate of a chemical reaction without being used up itself. It can be used over and over again.

  43. Rates of Reaction 5. Using a catalyst A catalyst is a substance which increases the rate of a chemical reaction without being used up itself. It can be used over and over again. A catalyst lowers the activation energy – the amount of energy needed for a successful collision. There are more collisions, and so a faster reaction.

  44. Activation energy What’s all this ‘ere talk about the ACTIVATION ENERGY?

  45. Activation energy What’s all this ‘ere talk about the ACTIVATION ENERGY? The ACTIVATION ENERGY is the relatively small amount of energy needed to start a chemical reaction

  46. Activation energy Activation energy reactants Used to break apart the old bonds Increasing energy products Time

  47. Activation energy Activation energy using a catalyst. Catalysts reduce the activation energy for the reaction – this makes the reaction go faster. reactants Increasing energy products Time

  48. Rate of reaction experiments

  49. Rate of reaction experiments 1. Surface area Boiling tube Time taken for magnesium to disappear = 109 secs Bubbles of hydrogen Magnesium ribbon Hydrochloric acid

  50. Rate of reaction experiments 1. Surface area Boiling tube Time taken for magnesium to disappear = 109 secs Time taken for magnesium to disappear = 55 secs Bubbles of hydrogen Magnesium ribbon Small pieces of Magnesium ribbon Hydrochloric acid

More Related