1

Given the following heats of combustion. CH3OH(l) + 3/2 O2(g) CO2(g) + 2 H2O(l) ΔH°rxn = ­726.4 kJ

C(graphite) + O2(g) CO2(g) ΔH°rxn = ­393.5 kJ

H2(g) + 1/2 O2(g) H2O(l) ΔH°rxn = ­285.8 kJ

Calculate the enthalpy of formation of methanol (CH3OH) from its elements. C(graphite) + 2 H2(g) + 1/2 O2(g) CH3OH(l)

What is the equation for the enthalpy of formation of sodium hypochlorite?

2

A quantity of 2.00 x 102 mL of 0.862 M HCl is mixed with 2.003 x 102 mL of 0.431 M Ba(OH)2 in a constant­pressure calorimeter that has a heat capacity of 453 J/°C. The initial temperature of the HCl and Ba(OH)2 solutions is the same at 20.48°C. For the following process the heat of neutralization is ­56.2 kJ. H+(aq) + OH­(aq) H2O(l)What is the final temperature of the mixed solution?

3

From the data shown below, calculate the enthalpy change for the following transformation. S(rhombic) S(monoclinic)(Monoclinic and rhombic are different allotropic forms of elemental sulfur.) S(rhombic) + O2(g) SO2(g) ΔH°rxn = ­296.06 kJS(monoclinic) + O2(g) SO2(g) ΔH°rxn = ­296.36 kJ

4

Calculate the heat of decomposition for this process at constant pressure and 25°C. (Look up the standard enthalpy of formation of the reactant and products in Table 6.4 and appendix; ΔH°f(BaCO3(s)) = ­1218.8 kJ/mol, ΔHf (BaO(s)) = ­558.2 kJ/mol and ΔH°f (Na2CO3(s)) = ­1130.9 kJ/mol, ΔH°f (Na2O(s)) = ­415.89 kJ/mol.)1 kJ CaCO3(s) CaO(s) + CO2(g)

5

A sheet of gold weighing 10.0 g and at a temperature of 18.0°C is placed flat on a sheet of iron weighing 20.0 g and at a temperature of 55.6°C. What is the final temperature of the combined metals? Assume that no heat is lost to the surroundings. (Hint: The heat gained by the gold must be equal to the heat lost by the iron.)

6

Methanol (CH3OH) is an organic solvent and is also used as a fuel in some automobile engines. From the following data, calculate the standard enthalpy of formation of methanol. 2 CH3OH(l) + 3 O2(g) 2 CO2(g) + 4 H2O(l) ΔH°rxn = ­1452.8 kJ

2 CH3OH(l) + 3 O2(g) 2 CO2(g) + 4 H2O(l) ΔH°rxn = ­1452.8 kJ

7

The values of the two allotropes of oxygen, O2 and O3, are 0 and 142.2 kJ/mol, respectively, at 25°C. Which is the more stable form at this temperature?

8

How much heat is required to change 255 g of ice at ­20 degrees C to steam at 135 degrees C. cp ice = 2.05 J/gC, cp steam = 2.08 J/gC.