Module 2: Born Haber Cycles Find the standard enthalpy of formation of ethane. Given the following enthalpies of combustion; C(s) = -393 KJ mol-1 H2(g) = -286 KJ mol-1 C2H6(g) = -1560 KJ mol-1

Step 1: Write equations for the data provided C(s) + O2  CO2(g) H2(g) + ½ O2(g)  H2O(l) C2H6(g) + 7/2 O2  2CO2(g) + 3H2O(l)

Step 2: Write an equation for what you want to find. 2C(s) + 3H2(g)  C2H6(g) Start your cycle with the left hand side of this equation.

Step 3: The Cycle Hf[C2H6] 2C(s) + 3H2(g) C2H6(g) 2Hc[C] 2CO2(g) + 3H2(g) Hc[C2H6] 3Hc[H2] 2CO2(g) + 3H2O(l)

Step 4: Calculation Hf[C2H6(g)] = = -84 KJ mol-1 2(-393) + 3(-286) + (1560) = -84 KJ mol-1