practical

• • ENERGY TRANSFER in chemical reactions can be measured by monitoring TEMPERATURE CHANGES.
  • The LARGER the temperature change, the LARGER the energy transferred.
• investigate how the amount of reactants in a reaction affects the amount of energy transferred.

  • Variables like REACTANT MASS & CONCENTRATION can be investigated.

  
• Insulation

  Use a POLYSTYRENE CUP with a lid for insulation to minimise energy loss to the surroundings.

  A) lid

  B) polystyrene cup

  C) thermometer

  
• the method can be used measure the energy change in:

  • NEUTRALISATION REACTIONS
  • reactions of METALS with ACIDS
  • DISPLACEMENT reactions
  • reactions between CARBONATES & ACIDS
• Method for a Neutralisation Reaction:

  • Prepare solutions the acid & alkali with known concentrations
  • Measure the INITIAL TEMPERATURE of the solutions
  • Mix the reactants in the insulated cup & immediately cover with a lid to prevent heat loss
  • Stir the solution
  • Measure the temperature at regular intervals (e.g. every 30 seconds) & record the HIGHEST temperature reached
  • Calculate the temperature difference between the initial & highest temp readings
  • Repeat this process for DIFFERENT CONCENTRATIONS of acid

  
• Method for a Reaction between an Acid & a Metal:

  • measure volume of acid to the insulated cup
  • Measure the INITIAL TEMPERATURE of it with a thermometer
  • Add a KNOWN MASS of the metal & immediately cover with a lid to prevent heat loss
  • Stir
  • Measure the temp at regular intervals (e.g. every 30 seconds) & record the HIGHEST temperature reached
  • Calculate the temp difference between the initial & highest temp readings

  
• • use a glass beaker
  • insulate the metal container
  • add a lid
  • measure copper sulfate with a pipette
  • use same volume of copper sulfate solution
  • use a more accurate balance
  • stir the mixture
  • record the initial & highest temp
  • use a digital thermometer
  • repeat the experiment & calculate the mean, ignoring anomalous results

  
• • volume of copper sulfate solution
  • concentration of copper sulfate solution
  • starting temp of copper sulfate solution