A sample of liquid butane \(\left(\mathrm{C}_{\mathrm{L}}
\mathrm{H}_{10}\right)\) in a pressurized lighter is set up directly
beneath an aluminum can, as show in the diagram above. The can contains
100.0 \(\mathrm{mL}\) of water, and when the butane is ignited the temperature
of the water inside the can increases from \(25.0^{\circ} \mathrm{C}\) to
\(82.3^{\circ} \mathrm{C}\) . The total mass of butane
ignited is found to be 0.51 \(\mathrm{g}\) , the specific heat of water is \(4.18
\mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C},\) and the
density of water is \(1.00 \mathrm{g} / \mathrm{mL} .\)
(a) Write the balanced chemical equation for the combustion of one mole of
butane in air.
(i) How much heat did the water gain?
(ii) What is the experimentally determined heat of combustion for
(ii) Whane based on this experiment? Your answer should be in \(\mathrm{kJ} /
\mathrm{mol}\) .
(c) Given butane's density of 0.573 \(\mathrm{g} / \mathrm{mL}\) at \(25^{\circ}
\mathrm{C},\) calculate how much heat
would be emitted if 5.00 \(\mathrm{mL}\) of it were combusted at that
temperature.
(d) The overall combustion of butane is an exothermic reaction. Explain
why this is, in terms of bond energies.
(e) One of the major sources of error in this experiment comes from the
heat that is aboorbed by the air. Why, then, might it not be a good ide to
perform this experiment inside a sealed container to prevent the heat from
leaving the system?