This Week's Puzzle

This assignment is due before 9 AM, Friday, October 13th, 2000.

  • This puzzle is worth 10 points of extra credit.
  • Answers must be accompanied by valid reasoning. Unlike the tests, the answer alone isn't enough!
  • Each week, the first student to submit a correct answer will recieve the stylish Chemistry Nomenclature Flash Cards
    (or a better prize when Dr. Blake can get his hands on some better prizes!).
  • Please enter your solution in the text area at the bottom of this page. DON'T FORGET TO GIVE YOUR NAME!

"Nutrition and Thermodynamics"

Due 9:00 AM Friday, October 13, 2000

If you drink alcoholic beverages, please do so in moderation and in accordance with applicable laws. NEVER, EVER operate machinery or motor vehicles while under the influence of alcohol.

Alcohol is a fuel. It can be burned to release energy and is sometimes even used in alternative gasoline mixtures (gasohols).

The potential energy we can obtain by metabolizing food is expressed in calories, a unit of energy. A "food calorie" is equal to 1000 regular calories. As you can see on the nutritional label above, metabolizing one gram of fat provides 9 calories of energy to our bodies.

When watching a movie with a friend of mine, I was drinking a regular beer and she was drinking a light beer. My beer clearly contained 5.0% alcohol by volume. Hers was not labelled as to its alcohol content. Using the following nutritional information, I was able to calculate the % alcohol in her beer.
Nutritional Information Light Beer Regular Beer
Calories 110 145
Carbohydrates 6.6g 10.6g
Protein 0.9g 1.3g
Fat 0.0g 0.0g



1. How many calories are due to the alcohol content in each beer?

2. A regular beer is 5.0% by volume. Calculate the % alcohol in the light beer from the information from problem 1.

3. Calculate the number of calories by gram for alcohol.

4. Write a balanced equation for the combustion of ethanol.

5. Using the enthalpies of formation of reactants and products, evaluate the enthalpy change for the equation.
How does this compare to your answer to #3?

Don't forget to explain your answer as clearly as possible.


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