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Chemistry Heat of Reaction

Preparation

Safety

  • The shield will get HOT. Leave in place after experiment until calculation phase finished.
  • Burn the hexamine ONLY for the period recommended. If burnt for longer than two minutes the water will become too hot to handle safely without further precautions.
  • Use splint to light sample so that hand is not near burning sample

Aim

  1. Measure the heat of combustion of Hexamine

2. Investigate the safety issues involved

Extra Equipment

  1. Hexamine sample ~1g
  2. Scales accurate to 2dp
  3. Matches and 10-15cm long splint for lighting safely
  4. Stirrer

Method

  1. Add the hexamine sample to the crucible or hexamine holder and record combined weight
  2. Set up the clamp stand with shield and filled crucible in place
  3. Set up clamp for water container and remove, leaving clamp and other apparatus in place
  4. Record the weight of the water container
  5. Fill with about 75 ml of water and record weight of water and container together
  6. Place thermometer in water and once thermometer stabilized record temperature of water
  7. Use splint to light sample
  8. Quickly replace water container in clamp with ~1cm gap between hexamine and water sample
  9. Let Hexamine burn for about 1 minute, much longer and the water may become to hot (unsafe and greater inaccuracies)
  10. Measure final temperature of water while stirring and reweigh crucible and sample

Heat of Reaction

Preparation

Safety

  • The shield will get HOT. Leave in place after experiment until calculation phase finished.
  • Burn the hexamine ONLY for the period recommended. If burnt for longer than two minutes the water will become too hot to handle safely without further precautions.
  • Use splint to light sample so that hand is not near burning sample

Aim

  1. Measure the heat of combustion of Hexamine
  2. Line Callout 2 (No Border): CrucibleLine Callout 2 (No Border): HexamineLine Callout 2 (No Border): WaterLine Callout 2 (No Border): ShieldLine Callout 2 (No Border): ContainerLine Callout 2 (No Border): ThermometerInvestigate the safety issues involved

 Extra Equipment

  1. Hexamine sample ~1g
  2. Scales accurate to 2dp
  3. Matches and 10-15cm long splint for lighting safely
  4. Stirrer

Method

  1. Add the hexamine sample to the crucible or hexamine holder and record combined weight
  2. Set up the clamp stand with shield and filled crucible in place
  3. Set up clamp for water container and remove, leaving clamp and other apparatus in place
  4. Record the weight of the water container
  5. Fill with about 75 ml of water and record weight of water and container together
  6. Place thermometer in water and once thermometer stabilized record temperature of water
  7. Use splint to light sample
  8. Quickly replace water container in clamp with ~1cm gap between hexamine and water sample
  9. Let Hexamine burn for about 1 minute, much longer and the water may become to hot (unsafe and greater inaccuracies)
  10. Measure final temperature of water while stirring and reweigh crucible and sample

Results

Final temp of water °C
Initial temp of water °C
Change in temp (∆T) °C
Mass of beaker and water  g
Mass of beaker g
Mass of water(Mass) g
Initial mass of Hexamine and holder g
Final mass of Hexamine and holder g
Mass of Hexamine burnt g

Calculations

Use the data table and this formula to calculate:

  1. The total energy released
  2. The energy per gram of hexamine

E=Mass x ∆T x Cp

(NB.  Cp is the heat capacity, which for H2O is 4.2 J/g/°C)