One of the best-selling light, or low-calorie, beers is 4.2%
alcohol by volume and a 355-mL serving contains 110
Calories; remember: 1 Calorie = 1000 cal = 1 kcal. To
estimate the percentage of Calories that comes from
the alcohol, consider the following questions.
a balanced chemical equation for the reaction of ethanol,
C2H5OH, with oxygen to make carbon dioxide
(b) Use enthalpies of formation in Appendix
C to determine ΔH for this reaction.
(c) If 4.2% of
the total volume is ethanol and the density of ethanol
is 0.789 g/mL, what mass of ethanol does a 355-mL serving
of light beer contain?
(d) How many Calories are
released by the metabolism of ethanol, the reaction from
(e) What percentage of the 110 Calories comes
from the ethanol?
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Master Enthalpy of Formation with a bite sized video explanation from Jules Bruno