rates of reaction

• What can reactions be classified as?

  Fast or slow
• What does the rate of reaction measure?

  How fast the reaction happens
• How can the rate of reaction be observed?

  By measuring reactants used or products formed
• What is the formula for calculating the average rate of reaction?

  Average Rate = amount used or formed / time
• What are the methods to measure reaction rates?

  1. Precipitation
  2. Change in mass (gas given off)
  3. Volume of gas given off
• How does the precipitation method work for measuring reaction rates?

  • Mix two clear solutions
  • Place flask over a marked paper
  • Measure time until mark is obscured
  • Faster disappearance indicates a faster reaction
• What is the procedure for measuring change in mass during a reaction?

  1. Use a mass balance
  2. Measure mass loss as gas is released
  3. Faster drop indicates a faster reaction
  4. Reaction is complete when mass stops changing
  5. Plot graph of mass change against time
  6. Use safety precautions for harmful gases
• How is the volume of gas given off measured in a reaction?

  1. Use a gas syringe
  2. More gas indicates a faster reaction
  3. Reaction is complete when no more gas is produced
  4. Plot graph of gas volume against time
  5. Use appropriate syringe size to avoid accidents
• What is the average rate of reaction if 200 cm³ of reactant are used?

  Calculation needed based on time
• What happens if the gas produced in a reaction is harmful?

  You must take safety precautions
• Why is it important to use the right size gas syringe?

  To prevent blowing the plunger out