9. C6H12O6(s) + 6 O2(g) 6 CO2(g) + 6 + 2800 kJ → Occasionally, not all values are found in the table of thermodynamic data. For most substances it is impossible to go into a lab and directly synthesize a compound from its free elements. The heat of formation for the substance must be calculated by working backwards from its heat of combustion. Calculate the of C6H12O6(s) given the combustion reaction above along with the following ∆Hf information: Substance (kJ/mol) ∆Hf° CO2(g) −393.5 H2O(l) −285.8 10. The thermite reaction occurs when a mixture of powdered aluminum and iron(III) oxide is ignited with a magnesium fuse. Using enthalpies of formation, calculate the standard change in enthalpy for the thermite reaction: 2Al (s) + Fe2O3(s) A12O3(s) + 2Fe(s) → 11. Calculate the for this overall reaction 2 H3BO3(aq) B2O3(s) + 3 H2O(l) given the following ∆H → equations: H3BO3(aq) HBO2(aq) + H2O(l) = kJ/mol → ∆H −0.02 H2B4O7(aq) + H2O(l) 4 HBO2(aq) H = kJ/mol → ∆ −11.3 H2B4O7(aq) 2 B2O3(s) + H2O(l) H = 17.5 kJ/mol → ∆ 12. Calculate the change in energy that accompanies the following reaction given the data below. H2(g) + F2(g) 2 HF(g) → Bond Type _____ Bond Energy H−H 432 kJ/mol F−F 154 kJ/mol H−F 565 kJ/mol Answers listed in random order: 17.0, , 8.0 × 107, 14.4, ‒2,677, ‒1276, ‒26, −544, ‒850. ‒270, ‒5.6, ‒320, −10.7
9. C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 6 + 2800 kJ Occasionally, not all values are found in the table of thermodynamic data. For most substances it is impossible to go into a lab and directly synthesize a compound from its free elements. The heat of formation for the substance must be calculated by working backwards from its heat of combustion. Calculate the ∆Hf of C6H12O6(s) given the combustion reaction above along with the following information: Substance ∆Hf° (kJ/mol) CO2(g) −393.5 H2O(l) −285.8 10. The thermite reaction occurs when a mixture of powdered aluminum and iron(III) oxide is ignited with a magnesium fuse. Using enthalpies of formation, calculate the standard change in enthalpy for the thermite reaction: 2Al (s) + Fe2O3(s) → A12O3(s) + 2Fe(s) 11. Calculate the ∆H for this overall reaction 2 H3BO3(aq) → B2O3(s) + 3 H2O(l) given the following equations: H3BO3(aq) → HBO2(aq) + H2O(l) ∆H = −0.02 kJ/mol H2B4O7(aq) + H2O(l) → 4 HBO2(aq) ∆ H = −11.3 kJ/mol H2B4O7(aq) → 2 B2O3(s) + H2O(l) ∆ H = 17.5 kJ/mol 12. Calculate the change in energy that accompanies the following reaction given the data below. H2(g) + F2(g) → 2 HF(g) Bond Type _____ Bond Energy H−H 432 kJ/mol F−F 154 kJ/mol H−F 565 kJ/mol Answers listed in random order: ‒2,677, 17.0, ‒1276, ‒26, −544, ‒850. , ‒270, 8.0 × 107, ‒5.6, ‒320, 14.4, −10.7
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