Thermodynamics

• Define the term enthalpy of lattice formation

  Enthalpy change when 1 mol of a solid ionic compound is formed from its gaseous ions.
• Why does a calculation of the enthalpy of lattice formation of silver iodide based on a perfect ionic model give a smaller value than the value calculated?

  AgI contains covalent character, bonds holding the lattice together are stronger.
• What is calorimetry?


  Measurement of heat transfer in a system.
• Suggest one reason why the enthalpy change for this reaction cannot be determined directly by calorimetry?

  Not possible to prevent some dissolving.
• Describe an experiment to determine the enthalpy of solution?

  •Measure water with measuring cylinder

  • put this into polystyrene cup

  •add known mass of (MgCl2) or whatever ur putting in.

  •record initial temp

  •record temp at regular times intervals for 5+ mins or until trend is seen.

  •Plot temp vs time.

  •Extrapolate like to find the initial and final time.

  •q= mcAT( change in T)