PAG 01-moles determination

• What apparatus can be used to measure gas volume in a reaction?

  Gas syringe or water-filled measuring cylinder
• How can the number of moles of CO2 be calculated at room temperature and pressure?

  Use the equation n = V/24
• What is the ideal gas law rearranged to find moles if not at RTP?

  PV = nRT rearranged
• What is the value of R in the ideal gas law?

  8.31
• What type of balance is used to accurately measure mass?

  Digital balance to 2 decimal places
• How many moles of CuCO3 reacted if 15 moles of CO2 were produced?

  15 moles of CuCO3 reacted
• What is the ratio of CuCO3 to CO2 in the reaction?

  1:1
• How to find the percentage mass of CuCO3 in CuCO3.Cu(OH)2?

  1. Record mass of CuCO3.Cu(OH)2
  2. React with acid, measure CO2 volume
  3. Calculate moles of CO2 (n = V/24)
  4. Use reaction ratio to find moles of CuCO3
  5. Calculate mass of CuCO3 (n = mass/Molar mass)
  6. Calculate percentage: (mass of CuCO3/mass of CuCO3.Cu(OH)2) x 100
• Why is it important to quickly put the bung in the flask after adding sulfuric acid?

  To reduce CO2 escape during reaction
• What are three possible sources of error in measuring gas volume in a reaction?

  • Gas escaping before bung insertion
  • Incomplete reaction
  • Gas dissolving in water
• What safety precautions are necessary when using CuCO3.Cu(OH)2 and sulfuric acid?

  • Avoid ingestion; wash hands after use
  • Wear safety goggles to prevent irritation
  • Avoid skin contact with H2SO4