Hess’s Law Practice Problems #2
Name ______________________________ Per ___
1. Balance the following reaction with whole number coefficients: ___ C (s) + ___ H2 (g)  ___ C6H6(l)
Calculate the ΔH of the reaction above using the following reaction enthalpies:
Action: (I.e.: x2, ÷2, flip, flip and x2, leave)
Equation:
______ 2 C6H6(l) + 15 O2(g)  12 CO2(g) + 6 H2O(g)
ΔH = - 6542 kJ
______ C (s) + O2 (g)  CO2(g)
ΔH = - 394 kJ
______ 2 H2 (g) + O2(g)  2 H2O(g)
Enthalpy(ΔH):
Result:
ΔH = - 572 kJ
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Sum:
2. Balance the following reaction with whole number coefficients: ___ CH4(g)  ___ C2H6(g) + ___ H2(g)
Calculate the ΔH of the reaction above using the following reaction enthalpies:
Action: (I.e.: x2, ÷2, flip, flip and x2, leave)
Equation:
______ 2 H2(g) + O2 (g)  2 H2O(g)
Enthalpy(ΔH):
ΔH = - 571.6 kJ Result:
______ CH4(g) + 2 O2 (g)  CO2(g) +2H2O(g) ΔH = - 890.4 kJ
______ 2 C2H6(g) + 7 O2 (g)  6 H2O(g) + 4 CO2(g) ΔH = -3119.8 kJ
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Sum:
3. Balance the following reaction with whole number coefficients: ___ N2(g) + ___ O2(g)  ___ NO2(g)
Calculate the ΔH of the reaction above using the following reaction enthalpies:
Action: (I.e.: x2, ÷2, flip, flip and x2, leave alone, etc.)
Equation:
______ N2(g) + O2(g)  2 NO(g)
ΔH = + 180 kJ
______ 2NO2(g)  2 NO(g) + O2(g)
ΔH = -112 kJ
Enthalpy(ΔH):
Result:
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Sum:
4. Balance the following reaction with whole number coefficients: ___ N2O3 (g)  ___ NO (g) + ___ NO2 (g)
Calculate the ΔH of the reaction above using the following reaction enthalpies:
Action: (I.e.: x2, ÷2, flip, flip and x2, leave alone, etc.)
Equation:
Result:
______ 2 N2(g) + 3 O2(g)  2 N2O3(g) ΔH = +83.7 kJ
______ N2(g) + O2(g)  2 NO(g)
ΔH = + 180.4 kJ
______ N2(g) + 2 O2(g)  2 NO2 (g)
ΔH = + 33.2 kJ
Enthalpy(ΔH):
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Sum:
5. Balance the following reaction with whole number coefficients: ___ FeO(s) + ___ CO (g)  ___ Fe(s) + ___ CO2(g)
Calculate the ΔH of the reaction above using the following reaction enthalpies:
Action: (I.e.: x2, ÷2, flip, flip and x2, leave)
Equation:
Result:
______ 3Fe2O3 (s) + CO(g)  2 Fe3O4(s) + CO2(g) ΔH = -48.3 kJ
Enthalpy(ΔH):
______ Fe2O3 (s) + 3 CO (g)  2 Fe(s) + 3 CO2(g) ΔH = - 23.4 kJ
______ Fe3O4 (s) + CO(g)  3 FeO(s) + CO2(g) ΔH = +21.8 kJ
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Sum:
6. Balance the following reaction with whole number coefficients: ___ H2(g) + ___ N2(g) + ___ O2(g) ___ HNO2(aq)
Calculate the ΔH of the reaction above using the following reaction enthalpies:
Action: (I.e.: x2, ÷2, flip, flip and x2, leave alone, etc.)
Equation:
Result:
______ NH4NO2(aq)  N2(g) + 2 H2O(l)
ΔH = -320.1 kJ
______ NH3(aq) + HNO2(aq)  NH4NO2(aq)
ΔH = -37.7 kJ
______ 2 NH3(aq)  N2(g) + 3 H2(g)
ΔH = +169.9 kJ
______ 2 H2(g) + O2(g)  2 H2O(l)
Enthalpy(ΔH):
ΔH = -571.6 kJ
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Sum: