Question

1) 2H2O(g) → 2H2 (g) + O2 (g) DH = 483.6 kJ

If 5 moles of water vapor decompose to form hydrogen and oxygen gas at a pressure of 1.0 atm and 125 oC, what is the change in internal energy of the system?

2)How much heat (in kJ) is evolved when 266 g of white phosphorus (P4 ) burn in air?

P4 (s) + 5O2 (g)---> P4O10(s) DH = -3013 kJ

3) A quantity of 1.00 × 102 mL of 0.500 M HCl was mixed with 1.00 × 102 mL of 0.500 M NaOH in a constant pressure calorimeter of negligible heat capacity. The initial temperature of the HCl and NaOH solutions was the same, 22.5°C, and the final temperature of the mixed solution was 25.9°C. Calculate the heat change for the neutralization reaction on a molar basis:

NaOH(aq)+HCl(aq)---> NaCl(aq)+H2O(l)

Assume that the densities and specific heats of the solutions are the same as for water (1.00 g/mL and 4.184 J/g·°C, respectively)

4) Choose the thermochemical equation that illustrates ΔH° f for Li2SO4 .

A) 2 Li+ (aq) + SO4 2- (aq) → Li2SO4 (aq)

B) 2 Li(s) + 1/8 S8(s, rhombic) + 2 O2 (g) → Li2SO4 (s)

C) Li2SO4 (aq) → 2 Li+ (aq) + SO4 2- (aq)

D) 8 Li2SO4 (s) → 16 Li(s) + S8(s, rhombic) + 16 O2 (g)

E) 16 Li(s) + S8(s, rhombic) + 16 O2 (g) → 8 Li2SO4 (s) C]

5) Which of the following reactions represents a formation reaction?

5O2 (g) + 2C2H2 (g)→ 2H2O (l) + 4CO2 (g)

CO2 (g) → C (graphite) (s) + O2 (g)

Ca (s) + CO2(g) + ½ O2 (g) → CaCO3(s)

Ca (s) + ½ O2 (g) → CaO (s)

*I want to check over the answers I got for these so if you could show full work/ explanations it would be much appreciated!