What is the 'rate' of a chemical reaction?

A measure of how quickly the reactants are converted into products.

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What is the formula for calculating the rate of a chemical reaction?

rate of reaction = time takenamount of reactant used up or product formed​

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What are 3 different ways of measuring the rate of a reaction?

  1. Measuring a decrease in mass.
  2. Measuring the volume of gas given off.
  3. Timing how long a precipitate takes to form.

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Give 5 factors that affect the rate of a chemical reaction.

  1. Surface area (of solids).
  2. Concentration (of solutions).
  3. Pressure (of gases).
  4. Temperature.
  5. Presence of a catalyst.

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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 increases.
  2. This increases the frequency of effective collisions, and so increases the rate of reaction.

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

  1. As the surface area of a solid increases, the number of particles on the surface available to collide and react increases.
  2. This increases the frequency of effective collisions, and so increases the rate of reaction.

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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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On a concentration vs. time graph of a chemical reaction, what does a steep gradient of the line indicate?

A steep line signifies that the rate of reaction was fast.

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Why do concentration vs. time graphs plateau?

The graph plateaus as the reactants are used up.

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What is the formula to find the gradient of a line?

gradient = ΔxΔy​

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How do you find the rate of reaction at a particular point on a concentration vs. time graph?

  1. Draw a tangent to the line at that point.
  2. Calculate the gradient of this tangent using the equation gradient = ΔxΔy​.

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What is meant by the term effective collision?

An effective collision is a collision between two particles that results in a reaction.

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