1. 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) = KJ mol-1

2. 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)

3. 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.

4. 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)

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