Physics

Energetics Worksheet
1. Calculate a value for the Lattice Energy of Calcium Chloride from the following data. Draw energy cycles
Std. Enthalpy of Formation of CaCl2 = - 795 kJ/ mol
Std. enthalpy of atomisation of calcium = + 177 kJ/mol
Std. enthalpy of atomisation of Chlorine = +121 kJ/mol
1st ionisation energy of calcium = +590 kJ/mol
2nd ionisation energy of calcium = +1100 kJ/mol
Electron Affinity of chlorine = -364 kJ/mol
2. Draw Born-Haber cycles and calculate the L.E. of Cu2O and CuO given:
∆Hf (Cu2O) = -166.7 kJ/mol
∆Hf(CuO) = -155.2 kJ/mol
1st I.E. (Cu) = +750 kJ/mol
2nd I.E. (Cu) = +2000 kJ/mol
∆Hat (Cu) = +339.2 kJ/mol
1st E.A. (O) = -141.4 kJ/mol
2nd E.A. (O) = +790.8 kJ/mol

3. 100 cm3 of 0.5 mol/dm3 ethanoic acid were mixed with 100cm3 of 0.5 mol/dm3 NaOH. The temperature rose from 18.2°C to 21.45°C. Calculate the Std. Enthalpy of Neutralisation in kJ/mol . c= 4.2 JK-1g-1
4. 50 cm3 of 0.4mol/dm3 NaOH required 20cm3 of 0.5mol/dm3 H2SO4 for neutralisation. The temp. rise was 3.9°C. Calculate ∆Hneut.
5. Assume that : C(s) + O2(g) →CO2(g), ∆H= -394kJ/mol H2(g) + ½ O2(g)→H2O(l), ∆H= -286 kJ/mol
(i) Calculate the ∆Hf of methane given its ∆Hc is – 895 kJ/mol.
(ii) Calc. the ∆Hf of ethanol given its ∆Hc is -1400 kJ/mol.
(iii) Calc. the ∆Hc of methanol given its ∆Hf is -239 kJ/mol.
(iv) Calc. the ∆Hf of Carbon Monoxide ,given its ∆Hc is -284 kJ/mol.
(v) Calc. the ∆Hf of carbon disulphide, given:
S(s) + O2(g)→SO2(g) , ∆H = -294 kJ/mol
CS2(l) + 3O2(g)→CO2(g) + 2SO2(g) ∆H = -1072 kJ/mol
6. Use the following Bond Energies/ kJ/mol: Calculate the std. enthalpy change for the following reactions:
(i) C2H4 (g) + H2 (g) →C2H6 (g)
(ii) the combustion of 1 mole of CH4.

7. Calculate the std enthalpy change for the foll. reaction:
SO2 (g) + 2H2S(g) → 3S(s) + 2H2O(l)
Given the following ∆Hf/ kJ/mol:
SO2 -297 ; H2S -20.2 ; H2O - 286

8.