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The Rate and Extent of Chemical Change

Factors which affect the rates of chemical reactions

  • 3 things to know
  • Paper 2

Overview

The five factors that affect rate, the effects of concentration, temperature, surface area, gas pressure and catalysts, investigating concentration by gas volume and by the disappearing cross, why rate is proportional to one over the time taken, identifying variables, and writing a hypothesis.

What you need to know

Answer each one before you reveal it.

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Key term

Describe the disappearing cross method for investigating how concentration affects rate, how the time relates to rate, and why one person judges the end point.

Key term

Name the independent variable, the dependent variable and two control variables in an investigation of how concentration affects rate.

Key term

Name the five factors that affect the rate of a chemical reaction.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Name the five factors that affect the rate of a chemical reaction.

    Model answer

    The concentration of reactants in solution, the pressure of reacting gases, the surface area of solid reactants, the temperature, and the presence of a catalyst.

  2. 2

    Name the factor that can alter the rate of a reaction between gases but has no equivalent effect on a reaction between two solutions.

    Model answer

    The pressure of the reacting gases.

  3. 3

    Name the factor that is changed when a lump of a solid reactant is ground into a fine powder.

    Model answer

    The surface area of the solid reactant.

  4. 4

    State the effect on the rate of reaction of increasing the concentration of a reactant in solution.

    Model answer

    The rate of reaction increases.

  5. 5

    State the effect on the rate of reaction of raising the temperature.

    Model answer

    The rate of reaction increases.

  6. 6

    State the effect on the rate of reaction of using a powdered solid in place of a single lump of the same mass.

    Model answer

    The rate of reaction increases.

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