Academic Chemistry Hess’s Law Worksheet Name: ______

1. From the following enthalpy changes,

o C + ½ O2  CO H = -110.5 kJ

o CO + ½ O2  CO2 H = -283.0 kJ

o calculate the value of H for the reaction: C + O2  CO2

2. From the following enthalpy changes,

o 2P + 3Cl2  2PCl3 H = -640 kJ

o 2P + 5Cl2  2PCl5 H = -886 kJ

o calculate the value of H for the reaction: PCl3 + Cl2  PCl5

3. From the following enthalpy changes,

o C2H5OH + 3O2  2CO2 + 3H2O H = -1234.7 kJ

o CH3OCH3 + 3O2  2CO2 + 3H2O H = -1328.3 kJ

o calculate the value of H for the reaction: C2H5OH  CH3OCH3

4. From the following enthalpy changes,

o Cu + Cl2  CuCl2 H = -206 kJ

o 2Cu + Cl2  2CuCl H = -136 kJ

o calculate the value of H for the reaction: CuCl2 + Cu  2CuCl 5. From the following enthalpy changes,

o H2 + F2  2HF H = -542.2 kJ

o 2H2 + O2  2H2O H = -571.6 kJ

o calculate the value of H for the reaction: 2F2 + 2H2O  4HF + O2

6. From the following enthalpy changes,

o Xe + F2  XeF2 H = -123 kJ

o Xe + 2F2  XeF4 H = -262 kJ

o calculate the value of H for the reaction: XeF2 + F2  XeF4

7. From the following enthalpy changes,

o 4NH3 + 5O2  4NO + 6H2O H = -1170 kJ

o 4NH3 + 3O2  2N2 + 6H2O H = -1530 kJ

o calculate the value of H for the reaction: N2 + O2  2NO

8. From the following enthalpy changes,

o 2Al + 1.5O2  Al2O3 H = -1601 kJ

o 2Fe + 1.5O2  Fe2O3 H = -821 kJ

o calculate the value of H for the reaction: 2Al + Fe2O3  2Fe + Al2O3 9. From the following enthalpy changes,

o H2O2  H2O + ½ O2 H = -94.6 kJ

o H2 + ½ O2  H2O H = -286.0 kJ

o calculate the value of H for the reaction: H2 + H2O2  2H2O

10. From the following enthalpy changes,

o C + O2  CO2 H = -393.5 kJ

o H2 + ½ O2  H2O H = -285.8 kJ

o 2C2H2 + 5O2  4CO2 + 2H2O H = -2598.8 kJ

o calculate the value of H for the reaction: 2C + H2  C2H2