2

• What is the first step in Method 1 for measuring enthalpy change?

  Weigh anhydrous copper(II) sulfate accurately
• Why should the stock of solid be kept in a closed container during weighing?

  To prevent moisture absorption from the air
• How much anhydrous copper(II) sulfate should be weighed for the experiment?

  Between 3.90-4.10 g
• What should be done with the containers before weighing the solid?

  • Wash the containers with the solution to be used
  • Dry the cup after washing
• What is the initial volume of water used in the experiment?

  25 cm³ of deionised water
• What should be recorded at minute intervals during the experiment?

  The temperature of the water
• What should be done to ensure accurate temperature readings?

  Stir the liquid continuously
• Why are polystyrene cups used in this experiment?

  They are good insulators with high heat capacity
• When should the powdered anhydrous copper(II) sulfate be added?

  At the fourth minute
• What should be done after adding the copper sulfate?

  Continue recording temperature every minute
• What is the purpose of plotting a graph of temperature against time?

  To determine the temperature change at the fourth minute
• What are the safety precautions to take during the experiment?

  • Avoid skin contact with chemicals
• What are some potential errors in the enthalpy change measurement?

  • Heat transfer to surroundings
  • Assumption of heat capacity of water
  • Neglecting calorimeter's heat capacity
  • Incomplete or slow reactions
  • Evaporation of water
  • Changes in room temperature
• How can accuracy be improved in the experiment?

  • Use an electronic temperature sensor
  • Employ data logging software
  • Use a flame calorimeter
• What is a feature of a flame calorimeter that improves accuracy?

  It burns fuel in pure oxygen
• What material is the spiral chimney of a flame calorimeter made from?

  Copper
• What is the purpose of using a lid on the polystyrene cup?

  To minimize heat loss during the reaction
• Why is it important to measure the temperature of both solutions before addition?

  To obtain a better average temperature
• What should be done if the two reactants are solutions?

  Measure the temperature of both before addition