I need help this problem??!

Question

For each of the following 3 fuels:

a. Determine ΔG°rxn for the combustion reaction: a “fuel” + b O2(g) → c CO2(g) + d H2O(g)

b. How much Gibb’s Free Energy is liberated by burning 34.274g of the fuel?

c. How much energy is liberated per gram of fuel burned?

d. If the CO2(g) produced by these reactions is collected at 32.19°C and 1.0134atm of pressure, what is the volume of CO2(g) produced by each reaction per kilojoule of energy liberated?

**3 fuels are: C2H2, C2H4, and C2H5OH

Substance ΔH°f (kJ/mol) S° (J/mol*K) ΔG°f (kJ/mol)

C2H2(g) +229.37 +203.27 +63.67

C2H4(g) +55.78 +214.46 +65.81

C2H5OH(l) -279.57 +164.92 -176.36

O2(g) 0 +209.53 0

H2O(g) -241.72 +189.82 -227.39

CO2(g) -393.31 +216.8 -392.37

Answer 1

I'll do the first one, and hopefully you will be able to do the other two.

C₂H₂

Write the correctly balanced equation for complete combustion

2C₂H₂ + 5O₂ ==> 4CO₂ + 2H₂O

a). ∆Gºrxn = ∑∆Gº_products - ∑∆Gº_reactants = [(4x-392.37)] + [(2x-227.39) - [(2x63.67) + (0)] = -1897 kJ

b). 34.274 g C2H2 x 1 mol C2H2 / 26.04 g x -1897 kJ / 2 mol C2H2 = 1248 kJ = ∆Gº for 34.274 g C2H2

c). Not sure how to answer this because we can calculate heat energy (∆H) or we can calculate useable energy (∆G) where ∆G = ∆H - T∆S. Or we could calculate total energy (∆H + ∆Gº). Which do they want?

d). Find mols CO2 produced per kJ and then use ideal gas law to find volume of CO2

2 mol C2H2 / 1897 kJ x 4 mol CO2 / 2 mol C2H2 = 0.002109 mol CO2 / kJ

PV = nRT

V = nRT / P = (0.002109)(0.0821)(305.3) / 1.0134

V = 0.05217 L

C₂H₄

C₂H₄ + 3O₂ ==> 2CO₂ + 2H₂O

C₂H₅OH

2C₂H₅OH + 7O₂ ==> 4CO₂ + 6H₂O