Consider covalent Compare lattice enthalpies Students construct solution character of ionic from Born–Haber cycles enthalpy cycles for different compounds. with those from calculations compounds. based on a perfect ionic Practical activity: Use solution enthalpy model to provide evidence Find the enthalpy of solution of KCl, cycles for ionic for covalent character in CaCl2, FeCl3, LiCl and NaCl compounds. ionic compounds. Construct energy cycles linking lattice enthalpies, hydration energies and enthalpies of solution. Define the term enthalpy of hydration. Perform calculations of an enthalpy change using these cycles. 3.1.8.2 1.0 Predict the sign of an Students predict the sign of the June 2013 Tutorial on the direction of chemical Gibbs free-energy and weeks entropy change and entropy change for some given Unit 5 Q3 reactions entropy. calculate entropy changes reactions. from absolute entropy January 2012 Understand the concept values. Calculate and for different Unit 5 Q2 ΔS ΔH of disorder/entropy. reactions, and use the values to Use the relationship calculate at 298 K. June 2011 ΔG Understand that the = TΔS to calculate Unit 5 Q2 ΔG ΔH – balance between and how this is related Use the values to predict the ΔG ΔG entropy and enthalpy to the feasibility of a feasibility of reactions. June 2010 determines the reaction. Unit 5 Q6
Consider covalent character of ionic compounds. Use solution enthalpy cycles for ionic compounds. Compare lattice enthalpies from Born–Haber cycles with those from calculations based on a perfect ionic model to provide evidence for covalent character in ionic compounds. Construct energy cycles linking lattice enthalpies, hydration energies and enthalpies of solution. Define the term enthalpy of hydration. Perform calculations of an enthalpy change using these cycles. Students construct solution enthalpy cycles for different compounds. Practical activity: Find the enthalpy of solution of KCl, CaCl2, FeCl3, LiCl and NaCl 3.1.8.2 Gibbs free-energy and entropy. Understand the concept of disorder/entropy. Understand that the balance between entropy and enthalpy determines the 1.0 weeks Predict the sign of an entropy change and calculate entropy changes from absolute entropy values. Use the relationship ΔG = ΔH – TΔS to calculate ΔG and how this is related to the feasibility of a reaction. Students predict the sign of the entropy change for some given reactions. Calculate ΔS and ΔH for different reactions, and use the values to calculate ΔG at 298 K. Use the ΔG values to predict the feasibility of reactions. June 2013 Unit 5 Q3 January 2012 Unit 5 Q2 June 2011 Unit 5 Q2 June 2010 Unit 5 Q6 Tutorial on the direction of chemical reactions
AQA-7405-B-SOW.DOCX