Problem: One of the best-selling light, or low-calorie, beers is 4.2 % alcohol by volume and a 12-oz 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) Write a balanced chemical equation for the reaction of ethanol, C2H5OH, with oxygen to make carbon dioxide and water. (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 12-oz serving of light beer contain? (d) How many Calories are released by the metabolism of ethanol, the reaction frompart (a)? 

FREE Expert Solution

ΔH˚rxn:


ΔH°rxn=ΔH°f, prod-ΔH°f, react


Combustion produces CO2 and H2O

  • Complete reaction: C2H5OH + O→ CO2 + H2O
    • add coefficients to balance (same number of atoms for both sides) 
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Problem Details

One of the best-selling light, or low-calorie, beers is 4.2 % alcohol by volume and a 12-oz 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) Write a balanced chemical equation for the reaction of ethanol, C2H5OH, with oxygen to make carbon dioxide and water. 

(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 12-oz serving of light beer contain? 

(d) How many Calories are released by the metabolism of ethanol, the reaction from
part (a)? 

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