Question

On a 12 day wilderness expedition you'll need to heat 3.0 kg of water to the boiling point each day. The air temperature will average 25 °C. You have available canisters of compressed propane C H fuel, which you'll burn to heat the water. Each canister has 75. g of propane in it. What is the minimum number of fuel canisters you must bring? The standard heat of formation of propane at 25 °C is – 103.85 kJ/mol. You'll probably find other helpful data in the ALEKS Data resource. canisters

Answer 1

Mass of water needed to heat = 12day× 3.0kg/day = 36.Kg

∆T = 100-25.0 = 75.0℃

Heat required to boil desired water = m.s.∆T = 36.×10³J×4.184J/g.℃ × 75℃ = 11296800J = 11296.8kJ

C₃H₈ +5 O₂ $\rightarrow$ 3CO₂ + 4H₂O(l).   

∆H =enthalpy of formation of products - enthalpy of formation of reactants

= 3 × (-393.51) +4×(-285.83) - 5×0 - (-103.85) = -2220.kJ/mol

Number of propane in one canister = 75.g/44.1g/mol = 1.701mol

Amount of heat released by one canister = 2220kJ/mol× 1.701mol = 3775.5kJ

Number of canister required = 11296.8kJ/3775.5kJ/canister

= 2.993 canister

Minimum number of fuel canister needed = 3. canisters (Answer)