6.E: Thermochemistry (Exercises)

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These are homework exercises to accompany the Textmap created for Chemistry: A Molecular Approach by Nivaldo Tro. Complementary General Chemistry question banks can be found for other Textmaps and can be accessed here. In addition to these publicly available questions, access to private problems bank for use in exams and homework is available to faculty only on an individual basis; please contact Delmar Larsen for an account with access permission.

Additional Questions

Q1

Propane, butane, ethanol, and white gas are all commonly used as fuel for camping. In this problem you will compare the efficiency of these four fuels.

a. First we will compare the energy content of the fuels by mass. Use standard heat of formation values to determine the amount of heat produced by the combustion of 100 grams of each fuel given:

i. Propane is C3H8
ii. Butane is C4H10
iii. Ethanol is C2H6O
iv. White gas is primarily isooctane, C8H18

b. Use the NIST Webbook web site to find the heat of combustion for each of the fuels and compare these results with the calculations based on the heat of formation values.

c. Look up the physical properties of each fuel to determine which are liquids and which are gases at room temperature.

d. Determine the mass that you need to carry with you if you go on a trip for 1 week, and expect to heat 1 gallon of water to boiling each day. Assume that the stove is 30% efficient. Liquid fuels can be transported in lightweight containers similar to metal water bottles, but gas fuels need to use heavier metal containers.