Thermodynamics

• State the meaning of the term enthalpy change:

  Heat energy change at constant pressure
• Define the term enthalpy of lattice formation:

  Enthalpy change when 1 mol of solid ionic compound is formed from its gaseous ions
• State why there is a difference between the theoretical and experimental values:

  Has partial covalent character
• State the meaning of the term enthalpy of electron affinity:

  The enthalpy change when one mole of electrons is added to a mole of gaseous atoms under standard conditions
• Give an equation to represent the process that occurs when the enthalpy of solution of magnesium chloride is measured:

  MgCl2(s) ---> Mg2+(aq) + 2Cl-(aq)
• Identify a reagent for identifying the presence of iodide ions in aqueous solution:

  Describe the observation:

  AgNO3

  Yellow ppt
• Describe how you would carry out an experiment to determine enthalpy of solution of anhydrous magnesium chloride:

  Explain how your results could be used to calculate enthalpy of solution:
• A reaction is exothermic and has a negative entropy change

  Which statement is correct?

  The reaction is feasible below a certain temperature
• Explain the difference between a enthalpy of formation value calculated based on the perfect ionic model and a calculated one

  ...
• Explain the difference between a enthalpy of formation value calculated based on the perfect ionic model and a calculated one

  ...
• Explain the meaning of the term 'perfect ionic model'

  Ions can be regarded as point charges
• Explain why the entropy is zero when the temperature is zero (kelvin)


  At absolute zero, particles are stationary, they do not vibrate - there is no disorder
• Explain whether or not a reaction is feasible

  The reaction is feasible if Gibbs value is negative