Standard enthalpy change of reaction

1) If a system loses 300 kJ of heat at the same time that it is doing 600 kJ of work, what is the change in the internal energy of the system?

2) Which of the following equations represents a reaction that provides the heat of formation of sodium hypochlorite (NaOCl)?

3) The heat of combustion for 1 mole of carbon to carbon dioxide is -410 kJ. How many kJ of heat would be liberated from the complete combustion of 60.0 g of carbon?

4) Given the following data at 1 atm of pressure and 25.0ºC:

DHºformation = +64.4 kJ/mole for Cu2+

DHºformation = -152.4 kJ/mole for Zn2+

DHºformation = 0 for both Zn and Cu because these are in the most stable state.

Calculate the standard heat of reaction for the following reaction:

Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)

5) The standard enthalpy of formation of propene, C3H6, is +20.6 kJ/mole. Calculate the heat of combustion of one mole of C3H6. The heats of formation of CO2(g) and H2O(l) are -394 kJ/mole and -285.8 kJ/mole respectively.-7.53 kJ/mole?

6) The standard enthalpy of formation of propane, C3H8, is -103.6 kJ/mole. Calculate the heat of combustion of one mole of C3H8. The heats of formation of CO2(g) and H2O(l) are -394 kJ/mole and -285.8 kJ/mole respectively.

7) Using the following information calculate the heat of formation of NF3.

NH3(g) + 3 F2(g) → NF3(g) + 2 HF(g)

DHº = -604.8 kJ

DHºf NH3(g) = -46.19 kJ/mole

DHºf HF(g) = -269 kJ/mole

8) Using the following information calculate the heat of formation of Fe2O3.

Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2(g)

DHº = -24.8 kJ

DHºf CO(g) = -110.5 kJ/mole

DHºf CO2(g) = -393.5 kJ/mole

9) Using the given standard enthalpies of formation and the heat of reaction, calculate the heat of formation of HNO3(aq).

3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)

DHº = -138.5 kJ

DHºf NO2(g) = +33.84 kJ/mole

DHºf NO(g) = +90.37 kJ/mole

DHºf H2O(l) = -285.85 kJ/mole

10) Use the given standard enthalpies of formation to determine the heat of reaction of the following reaction:

Fe2O3(s) + 2 H2(g) → 3 Fe(s) + 3 H2O(l)

DHºf Fe2O3(s) = -822.2 kJ/mole

DHºf H2O(l) = -285.9 kJ/mole

11) Calculate Hof (kJ) for the following reaction from the listed standard enthalpies of formation:

CO(g) + NH3(g) → HCN(g) + H2O(g)

DHºf CO(g) = -110.5 kJ

DHºf NH3(g) = -46.1 kJ

DHºf HCN(g) = +135.1 kJ

DHºf H2O(g) = -241.8 kJ

12) Use the given standard enthalpies of formation to determine the heat of reaction of the following reaction:

C3H6O(l) + 4 O2(g) → 3 CO2(g) + 3 H2O(l)

DHºf CO2(g) = -393.5 kJ/mole

DHºf H2O(l) = -285.8 kJ/mole

DHºf C3H6O(l) = -249.5 kJ/mole

13) Calculate the heat of reaction (kJ) using the listed heats of formation:

CH4(g) + 4 F2(g) → CF4(g) + 4 HF(g)

DHºf CH4 = -74.81 kJ/mole

DHºf CF4 = -925.0 kJ/mole

DHºf HF = -271.1 kJ/mole

14) Use the given standard enthalpies of formation to determine the heat of reaction of the following reaction:

2 C3H6(g) + 9 O2(g) → 6 CO2(g) + 6 H2O(l)

DHºf C3H6(g) = +53.5 kJ/mole

DHºf CO3(g) = -393.5 kJ/mole

DHºf H2O(l) = -285.9 kJ/mole

15) Use the given standard enthalpies of formation to determine the heat of reaction of the following reaction:

NH3(g) + 3 F2(g) → NF3(g) + 2 HF(g)

DHºf NH3(g) = -46.19 kJ/mole

DHºf NF3(g) = -113.0 kJ/mole

DHºf HF(g) = -269.0 kJ/mole

Solution Summary

The solution shows how to calculate the standard enthalpy change of reaction in detail.