measure the production of a gas (rates of reaction)

• What is the aim of the investigation?

  To investigate the effect of concentration
• What is produced when calcium carbonate reacts with hydrochloric acid?

  Calcium chloride, water, and carbon dioxide
• What is the chemical equation for the reaction?

  CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)
• How can the volume of carbon dioxide gas produced be measured?

  Using a gas syringe
• What is the method for conducting the reaction?

  1. Support a gas syringe with a stand, boss, and clamp.
  2. Add 50 cm³ of dilute hydrochloric acid to a conical flask.
  3. Add 0.4 g of calcium carbonate to the flask.
  4. Connect the gas syringe and start a stop clock.
  5. Record the volume of gas produced every 10 seconds.
  6. Clean the apparatus after the reaction.
  7. Repeat with different concentrations of hydrochloric acid.
• Hazards, risks and precautions

  Evaluate the hazards and the precautions needed to reduce the risk of harm.

  For example:

  Hazard

  Possible harm

  Possible precaution

  Hydrochloric acid

  Causes skin and eye irritation

  Wear eye protection

  Fizzing in the reaction mixture

  Acidic spray or foam escaping, which may damage skin and eyes

  Use a large conical flask so there is plenty of space inside; do not look over the top when adding the calcium carbonate
• What is the initial volume of gas produced at time 0 seconds?

  0 cm³
• What should be recorded in the results table?

  Time and volume of gas produced
• What should be plotted for each concentration of hydrochloric acid?

  • Volume of gas (cm³) on the vertical axis
  • Time (s) on the horizontal axis
  • Draw a curve of best fit
• How is the mean rate of reaction calculated?

  Mean rate = total volume of gas / reaction time
• What is the effect of increasing the concentration of acid on the mean rate of reaction?

  It increases the mean rate of reaction
• How can graphs and calculations help describe the effect of concentration on reaction rate?

  They show trends in reaction rates