Biology B2 4.1

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The cells in your body are like tiny chemical factories. Hundreds of different chemical reactions are taking place all the time. These reactions have to happen  fast - you need energy for your heart to beat and to hold your body upright. They also need to be very controlled. 

Chemical reactions can only take place when different particles collide. The reacting particles don't just have to bumo into each other. They need to collide with enough energy to react. 

The minimum amount of energy particles must have to be able to react is known as the activation energy. So you will make the reaction more likey to happen if you can make it:

  • more likely that reacting particles bump into each other
  • increase the energy of these collisions
  • reduce the activation energy needed

Q. What is the activation energy of a reaction?

A. It is the minimum amount fo energy needed for particles to be able to react with each other when they collide. 

Controlling the rate of reactions

In everyday life we control the rates of chemical reactions all the time. When you cook food, you incease the temperature to speed up chemical reactions. Somtimes we use special chemicals known as catalysts to speed up reacyions for us. 

A catalyst changes the rate of a chemical reaction, usually speeding it up. Catalysts are not used up…


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