GCSE Combined Science (AQA)

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Rate of Chemical Reactions

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Organisation Animal Tissues, Organs and Organ Systems

Rate of Chemical Reactions

3:45 Collision Theory and Rate of Reaction
Spec 4.2.2.1
Previous Enzymes & pH Next The Liver & Bile
  • Enzymes speed up the rate of chemical reactions.
  • Rate calculations are essential for understanding how quickly reactions occur.
  • The rate of change in reactions is calculated by dividing the amount of substrate used or product made by the time taken.
  • Biological washing detergents contain enzymes like lipase to break down fats and oils.
  • The breakdown of hydrogen peroxide by the enzyme catalyze produces water and oxygen.
  • Example calculation: 2 cm�� of oxygen produced in 100 seconds results in a rate of 0.02 cm�� per second, which equals 1.2 cm�� per minute when multiplied by 60.
  • Rate of change can also be determined graphically using the slope of a tangent to the curve on a graph of time versus amount of product.
  • The slope of the tangent represents the rate at a specific point and is calculated as vertical change divided by horizontal change.
  • Multiple tangents can be used to analyze how the rate changes over time in an experiment.

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