Give 4 factors that affect the rate of a chemical reaction.

  1. Temperature.
  2. Concentration of solution or pressure of gas.
  3. Surface area.
  4. Presence of a catalyst.

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Explain how increasing the temperature increase the rate of a reaction.

  1. As temperature increases, particles move around faster (have more kinetic energy).
  2. This means they will collide more frequently.
  3. They will also collide with more energy, so the collision is more likely have enough energy to react successfully (activation energy).

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Explain how increasing concentration or pressure increases the rate of a reaction.

  1. As the concentration of a solution (or the pressure of a gas) increases, the number of particles per unit of volume will increase.
  2. This will increase the frequency of collisions, and so increase the rate of reaction.

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Explain how increasing the surface area of a solid affects the rate of a reaction.

  1. If a reactant is solid, breaking it into smaller pieces increases the surface area to volume ratio.
  2. This means, for the same volume of solid, the particles will have a greater area over which they can collide, so will collide more frequently.
  3. More frequent collisions result in a greater number of reactions.

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What is collision theory?

Collision theory states that for particles to react, they have to collide with sufficient energy, and at the right orientation (direction).

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What is activation energy?

The minimum amount of energy that particles require to react together.

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Why do particles need activation energy?

They need energy to break the bonds of the reactants, so the reaction can begin.

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How does a catalyst increase the rate of reaction?

  1. Catalysts speed up reactions by lowering the activation energy required for a reaction to occur.
  2. They do this by giving an alternative route (reaction pathway) that requires less energy.

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How would the above reaction profile change in the presence of a catalyst?

The activation energy would be lower in the presence of a catalyst.

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