Chemistry

07. Indirect determination of an enthalpy change of reaction

  • 00:23 Why not use a glass beaker as a calorimeter?
  • 00:43 Why wait a while before measuring temperature?
  • 01:01 Why is it important to have the thermometer at eye-level?
  • 01:07 Why is it important to measure the HCl temperature for this initial period?
  • 01:27 Why use foil to cover the calorimeter?
  • 01:32 Why is it important to keep stirring the mixture?
  • 01:41 Why is it important to keep the foil in place whilst measuring the temperature?  
  • 01:49 Why is the temperature dropping? Where is the heat going?  
  • 01:58 Why is it important to re-weigh the emptied weighing boat?
  • 02:10 Why is it important to extrapolate to point of mixing (3min.) and not measure ΔT from point 3min. and 30s?

  • a digital balance (pref. 3 dec. place but minimum 2dp)

  • thermometer

  • simple calorimeter

  • 25.0 cm³ volumetric pipette with safety filler

  • stopwatch

  • spatula 

  • weighing boat 

Hazard Risk Control measure

2 mol dm-3 HCl solution

Contact with eyes & skin

Eye: Flood with tap water (10 min)

Skin: Drench with water

Dry MgCO3 & MgO

Contact with eyes

Eye: Flood with tap water (10 min)