ScholarshipThermochemistryFree

How efficient is a camping stove?

ΔcH theory vs experiment with calorimeter heat capacity, incomplete combustion energetics, fuel storage

A tramper tests a butane (

\ce{C4H10}

) gas canister stove. Burning 0.580 g of butane heats 200 g of water in an aluminium pot (heat capacity of the pot 45 J °C

^{-1}

) from 18.0 °C to 41.5 °C. A black deposit forms on the pot.

\Delta_fH

(kJ mol

^{-1}

\ce{C4H10(g)}

−126;

\ce{CO2(g)}

−394;

\ce{CO(g)}

−111;

\ce{H2O(l)}

−286. M(

\ce{C4H10}

) = 58.0 g mol

^{-1}

;

c

(water) = 4.18 J g

^{-1}

°C

^{-1}

Facts you may need

Hess's law
calorimetry with a container
incomplete combustion
intermolecular forces and pressure

(a)

Write the balanced equation for complete combustion and calculate

\Delta_cH

from the

\Delta_fH

data.

(b)

Calculate the experimental

\Delta_cH

, including the energy absorbed by the pot, and the efficiency of the stove.

(c)

The black deposit shows incomplete combustion. Write an equation for butane burning to carbon monoxide and water, calculate the energy released per mole of butane, and determine how much less energy this releases than complete combustion.

(d)

Evaluate the experiment: identify the main sources of the 28% shortfall and suggest two improvements, explaining how each would change the measured value.

(e)

Butane boils at −1 °C, yet it is stored as a liquid in a canister at room temperature. Explain, with reference to the particles and forces involved, and explain why butane stoves work poorly in alpine conditions at −10 °C.