Chemistry Rates of Reaction Revision

Chemistry Rates of Reaction Revision

1. Measuring rates of reaction

   • The rate of reaction can be measured by considering the amount of product formed or reactant used in a given period of time
   • The rate of reaction changes depending on how far through the reaction is!
   • The activation energy is the minimum amount of energy needed for a reaction to occur.
   • Gas produced? measure with gas syringe, burette or upside down measuring cylinder
     • Solid produced? measure with balance

2. The rate of an equation decreases with time. This is because the reactants are used up, resulting in fewer collisions.

3. The rate of reaction increases if the temperature is raised. This is because:

   • The reactant particles move more quickly, they have more kinetic energy
     • This means they move faster, which increases collision frequency
       • More collisions=faster reaction rate

4. Rate of reaction increases if pressure or concentration is increased.

   • Particles become more crowded, so collisions are more frequent
     • Rate of reaction increases.

5. Increasing the concentration of a reactant increases the rate of reaction.

   • Reactant particles become more crowded and there is a greater chance of collision.

6. rate of reaction = amount of reactant used or product formed

7. Surface area increases the rate of reaction.

   • More particles are exposed to the reactant.
     • Greater chance of collision, rate increases.

8. Catalysts increase the rate of reaction without being used up.

   • They lower the activation energy needed, so more collisions result in a reaction.
     • Lower costs - less energy is needed.

9. The rate of reaction is the speed at which a reaction happens.

10. Collision theory - reactant particles must collide with activation energy for reaction to occur.

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