# Rates of Reaction Presentation.pptx

11 de Mar de 2023
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### Rates of Reaction Presentation.pptx

• 1. Rates of Reaction 6 March 2023
• 2. Learning Objectives 3.9 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 3.10 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 3.11 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 3.12 know that a catalyst is a substance that increases the rate of a reaction, but is chemically unchanged at the end of the reaction
• 3. Learning Objectives 3.13 know that a catalyst works by providing an alternative pathway with lower activation energy 3.14C draw and explain reaction profile diagrams showing ΔH and activation energy 3.15 practical: investigate the effect of changing the surface area of marble chips and of changing the concentration of hydrochloric acid on the rate of reaction between marble chips and dilute hydrochloric acid 3.16 practical: investigate the effect of different solids on the catalytic decomposition of hydrogen peroxide solution
• 4. 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.
• 5. Rates of Reaction The ACTIVATION ENERGY is the minimum amount of energy required to cause the reaction to happen. Chemical reactions will only occur when the reacting particles collide with each other with sufficient energy so they react. There are FIVE very important factors which can affect the rate of reaction.
• 6. Rates of Reaction Temperature Pressure (of gases) Concentration Surface Area Catalyst https://wordwall.net/resource/ 53457112/rates-of-reaction
• 7. Rates of Reaction Question: How can we explain the rates of reaction using kinetic molecular theory?
• 8. Rates of Reaction Kinetic theory is all about the random movement of particles Kinetic theory assumes that particles are in constant random motion
• 9. Rates of Reaction Kinetic theory is all about the random movement of particles Kinetic theory assumes that particles are in constant random motion ! And there will be collisions! It’s these collisions that are the cause of chemical reactions.
• 10. Rates of Reaction 1. Temperature of the Reactants 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 High temperature Low temperature
• 11. Rates of Reaction 2. Concentration of the Dissolved Reactants 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 High concentration Low concentration
• 12. Rates of Reaction 3. Pressure (in gases) 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 High pressure Low pressure
• 13. Rates of Reaction 4. Surface area of solid reactants 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 large surface area small surface area
• 14. 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.
• 15. Activation Energy What’s this ACTIVATION ENERGY all about? The ACTIVATION ENERGY is the relatively small amount of energy needed to start a chemical reaction
• 18. Rates of Reaction Experiments 1. Surface area Increasing the surface area of reactants increases the rate of reaction
• 21. Rates of Reaction Experiments 2. Concentration Volume of thiosulphate Time for cross to disappear As the concentration of sodium thiosulphate increases, so the time taken decreases – the rate of reaction gets faster.
• 22. Rates of Reaction Experiments 3. Temperature Tempera ture of reaction mixture (oC) Reaction time (secs) Average reaction time (secs) Experiment 1 Experiment 2 Experiment 3 40 24 25 25 25 50 22 20 20 21 60 17 16 16 16 70 12 11 11 11 80 7 7 8 7
• 23. Rates of Reaction Experiments 3. Temperature Tempera ture of reaction mixture (oC) Reaction time (secs) Average reaction time (secs) Experiment 1 Experiment 2 Experiment 3 40 24 25 25 25 50 22 20 20 21 60 17 16 16 16 70 12 11 11 11 80 7 7 8 7 As the temperature increases so the time taken for the cross to disappear decreases – the reaction gets faster.
• 27. In this lesson we have covered: Rates of Reaction Activation Energy Rates of Reaction Experiments Rates of Reaction