What volume of fuel should you bring? assume each of the following: the fuel has an average formula of c7h16; 15% of the heat generated from combustion goes to heat the water (the rest is lost to the surroundings); the density of the fuel is 0.78 g/ml; the initial temperature of the water is 25.0 ∘c; and the standard enthalpy of formation of c7h16 is -224.4 kj/mol.

The volume in L is V=2.2L

Explanation:

Supposing the water will be boiled at no great elevation, so its boiling point will be 100°C:

7 C(s) + 8 H2(g) → C7H16(l), ΔH = -224.4 kJ/mol C7H16

C(s) + O2(g) → CO2(g), ΔH = -393.5 kJ/mol

H2(g) + ½ O2(g) → H2O(g), ΔH = -241.82  kJ/mol

Rearranging as necessary:

C7H16(l) → 7 C(s) + 8 H2(g), ΔH = +224.4 kJ

7 C(s) + 7 O2(g) → 7 CO2(g), ΔH = -2754.5 kJ

8 H2(g) + 4 O2(g) → 8 H2O(g), ΔH =  -1934.56 kJ

Add up all three equations:

C7H16(l) + 11 O2(g) → 7 CO2(g) +  8 H2O(g), ΔH = -4464.66 kJ

V=