1. Can you handle the enthalpy?
Solve these Hess’s Law Problems!

2. Question 1 Find the standard enthalpy for the reaction: Given that:
C(s) + ½O2(g)  CO(g)
Given that:
C(s) + O2(g)  CO2(g) ΔH= -394 kJ
CO2(g)  CO(g) + ½O2(g) ΔH= 283 kJ
Answer: kJ

3. Question 2 Find the standard enthalpy for the reaction: Given that:
Fe2O3 + 2Al  Al2O3 + 2Fe
Given that:
2Al + 3/2O2  Al2O3 ΔH= kJ
2Fe + 3/2O2  Fe2O3 ΔH= -824 kJ
Answer: kJ

4. Question 3 Find the standard enthalpy for the reaction: Given that:
2C2H6 + 7O2  4CO2 + 6H2O
Given that:
C2H4 + 3O2  2CO2 + 2H2O ΔH= kJ
C2H4 + H2  C2H ΔH= -137 kJ
H2 + ½O2  H2O ΔH= -242 kJ
Answer: kJ

5. Question 4 Find the change in enthalpy for the reaction: Given that:
NH4NO3  NH4+ + NO3-
Given that:
Answer: kJ
Substance
ΔHf
NH4NO3 kJ
NH4+ kJ
NO3- kJ

6. Question 5 Find the standard enthalpy for the reaction: Given that:
C2H4 + Cl2  C2H3Cl + HCl
Given that:
C2H4 + HCl  C2H5Cl ΔH= -65 kJ
C2H3Cl + H2  C2H5Cl ΔH= -140 kJ
H2 + Cl2  2HCl ΔH= -185 kJ
Answer: kJ

7. Question 6 Find the change in enthalpy for the reaction: Given that:
2H2S + 3O2  2H2O + 2SO2
Given that:
Answer: kJ
Substance
ΔHf
H2S
-20.1 kJ O2
0.0 kJ
H2O kJ
SO2 kJ

8. Question 7 Find the standard enthalpy for the reaction: Given that:
CaCO3 + 2HCl  CaCl2 + CO2 + H2O
Given that:
CaCO3  CaO + CO2 ΔH= 175 kJ
Ca(OH)2  H2O + CaO ΔH= 67 kJ
Ca(OH)2 + 2HCl  CaCl2 + 2H2O ΔH= -198 kJ
Answer: -90 kJ