# Rate of reactions

Medical Students
3 de Jan de 2015
1 de 17

### Rate of reactions

• 1. RATE OF CHEMICAL REACTIONS By student :Mustafa Jamal
• 2. RATE OF REACTIONS What does rate of reaction mean? The speed of different chemical reactions varies hugely. Some reactions are very fast and others are very slow. The speed of a reaction is called the rate of the reaction On :The rate of a reaction depends the frequency of collisions between particle the energy with which particles collide.
• 3. RATE OF REACTIONS For example rate for these reactions Iron rusting has a low reaction rate. This process is slow.
• 4. RATE OF REACTIONS Wood combustion has a high reaction rate. This process is fast.
• 5. RATE OF REACTIONS Nuclear explosion This process is very fast
• 6. RATE OF REACTIONS factors affect the rate of reactions 1: increased temperature 2: increased concentration of dissolved reactants,and increased pressure of gaseous reactants 3:increased surface area of solid reactants 4: use of a catalyst.
• 7. RATE OF REACTIONS 1 : Temperature A : When you raise the temperature of a system, the molecules bounce around a lot more. They have more energy. When they bounce around more, they are more likely to collide. That fact means they are also more likely to combine. B :When you lower the temperature, the molecules are slower and collide less. That temperature drop lowers the rate of the reaction.
• 8. RATE OF REACTIONS
• 9. RATE OF REACTIONS 2: concentration If there is more of a substance in a system, there is a greater chance that molecules will collide and speed up the rate of the reaction. If there is less of something, there will be fewer collisions and the reaction will probably happen at a slower speed.
• 10. RATE OF REACTIONS concentration
• 11. Pressure affects the rate of reaction, especially when you look at gases. The gas particles become closer together, increasing the frequency of collisions. This means that the particles are more likely to react. lower pressure higher pressure RATE OF REACTIONS
• 12. 3:increased surface area of solid reactants RATE OF REACTIONS
• 13. RATE OF REACTIONS
• 14. 4: use of a catalyst. A catalyst is a substance which speeds up a reaction, but is chemically unchanged at its end. When the reaction has finished, the mass of catalyst is the same as at the beginning.. Many catalysts are transition metals or their compounds. For example: Iron is a catalyst in the production of ammonia from nitrogen and hydrogen (the Haber process). RATE OF REACTIONS
• 15. Nickel is a catalyst in the production of margarine (hydrogenation of vegetable oils). RATE OF REACTIONS
• 16. catalysts Why are catalysts so important for industry?  Products can be made more quickly, saving time and money.  Catalysts reduce the need for high temperatures, saving fuel and reducing pollution. Catalysts are also essential for living cells. Biological catalysts are special types of protein called enzymes. RATE OF REACTIONS
• 17. Thank you for attention RATE OF REACTIONS