AQA GCSE Chemistry Topic 6: The Rate and Extent of Chemical Change Quiz

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10 Questions

What is the formula to calculate the rate of reaction in terms of amount of product formed over time?

Rate of reaction = amount of product formed

Which unit could be used for the rate of reaction when measuring quantity in terms of moles?


What does the activation energy represent in a chemical reaction?

Minimum energy required for a reaction to occur

How do factors like concentration and surface area influence the rate of a chemical reaction?

Lead to more collisions with less energy

Why is temperature considered a factor that affects the rates of chemical reactions?

To lower the activation energy required for reactions

What effect does increasing the temperature have on the rate of a chemical reaction?

Increases the rate of reaction

Which of the following best describes the role of catalysts in chemical reactions?

Speed up reactions without being consumed

Why are catalysts not included in the equation for a reaction?

They are not consumed in the reaction

What specific effect do enzymes have in biological systems as catalysts?

Speed up chemical reactions

How do catalysts affect the activation energy of a chemical reaction?

Decrease the activation energy needed

Study Notes

Calculating Rates of Reactions

  • Rates of reactions can be measured using the amount of reactant used or product formed over time
  • Formula for rate of reaction: Rate of reaction = amount of reactant used ÷ time or Rate of reaction = amount of product formed ÷ time
  • Quantity of reactant or product can be measured by mass in grams or by volume in cm³
  • Units of rate of reaction may be given as g/s or cm³/s
  • Quantity of reactants can also be measured in terms of moles, with units of rate of reaction as mol/s
  • To find the rate of reaction graphically, draw tangents to curves and use the slope of the tangent

Factors Affecting Rates of Chemical Reactions

  • Concentration of reactants
  • Pressure of reacting gases
  • Surface area of solid reactants
  • Temperature
  • Catalysts

Collision Theory and Activation Energy

  • Collision theory: chemical reactions can occur only when reacting particles collide with each other and with sufficient energy
  • Activation energy: the minimum amount of energy that particles must have to react
  • Increasing concentration, pressure, and surface area increases the frequency of collisions and thus the rate of reaction
  • Increasing temperature increases the frequency of collisions and makes them more energetic, thus increasing the rate of reaction


  • Substances that speed up chemical reactions without being changed or used up during the reaction
  • Enzymes act as catalysts in biological systems
  • Catalysts decrease the activation energy, increasing the proportion of particles with energy to react
  • Catalysts provide a different pathway for a chemical reaction with a lower activation energy

Test your knowledge on calculating rates of reactions, measuring rates of reactions, and understanding the factors affecting the rate of reaction. This quiz covers concepts related to the rate and extent of chemical change in the context of AQA GCSE Chemistry Topic 6.

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