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 = mass of product produced or lost ÷ time taken


or


rate = volume of product produced or lost ÷ time taken

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

  1. Precipitation and colour change.
  2. Change in mass.
  3. Volume of gas gained or lost.

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How can precipitation and colour change be used to measure the rate of a reaction?

  1. Precipitation - measure the time it takes for a mark (e.g black cross under flask) to disappear.
  2. Colour change - measure the time it takes for a colour change to occur.
  3. In both cases calculate the rate using: '1 ÷ time taken'.

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What are the 2 issues with measuring the rate of a reaction by observing colour change and precipitation?

  1. It is quite subjective - different people might interpret the exact point the solution changes colour differently.
  2. You can't use your results to plot a rate of reaction graph

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How can you calculate the rate of a reaction by measuring the change in mass?

  1. Use a balance to monitor how the mass changes over time.
  2. Take measurements at regular intervals.
  3. Plot your results on a graph.
  4. Draw a tangent and calculate its gradient to find the rate at a particular time.

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What is the most accurate way to measure the rate of a reaction and why?

Change in mass, because the balance (scale) is the most accurate measuring device.

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How can you use a gas syringe to measure the rate of a chemical reaction?

  1. Use the gas syringe to monitor how the volume of gas changes over time.
  2. Take measurements at regular intervals.
  3. Plot your results on a graph.
  4. Draw a tangent and calculate its gradient to find the rate at particular time.

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