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Week 5 Exercises
CHM/109 Version 2

University of Phoenix Material
Week 5 Exercises
Prepare written answers to the following exercises:
1. Adapted from Exercise 36 in Ch. 11 of Introductory Chemistry:
A marine biologist may need to dive deep underwater for her research. To do so, she may want to
know how to do calculations related to pressure and volume changes that occur, depending on the
depth of the dive. Suppose she inhales air at a depth of 60 meters and at a pressure of 6 atm.
Holding her breath, the marine biologist then ascends to a depth of 10 meters (where the pressure is
now 2 atm). What volume would the air in her lungs expand to?
2. Environmental health and safety departments employ many environmental scientists to monitor and
regulate business practices. Imagine that you work for the Environmental Protection Agency (EPA) to
ensure that gas canisters are correctly pressurized.
You locate a canister that contains 0.72 moles of helium. However, the container is authorized by the
manufacturer and by the EPA to hold no more than 20 liters (L) of gas. A typical 0.5 moles of helium
gas occupies 13.0 L. Assume standard (STP) conditions.
a. Does the container containing 0.72 moles of helium follow EPA regulations?
b. Explain by determining the volume that 0.72 moles of helium gas would occupy if not
pressurized.
3. Imagine that you are an organic chemist who is looking for a substance that will be miscible in water,
yet contain carbon. You come across two compounds: CH3CH2CH2CH2CH3 and CH2OH. Which
one is miscible in water and why?

Copyright © 2013 by University of Phoenix. All rights reserved.



Week 6 Exercises
CHM/109 Version 2

University of Phoenix Material
Week 6 Exercises
Prepare written answers to the following exercises:
1. Imagine that you work at a company that prepares chemical solutions. You are asked to label a
solution to sell to different customers. One customer is a hospital, another is a chemistry lab at a
university, and a third is a physics lab at a university. You added 900 kg of NaCl in a 100-liter
container and filled it with water to a volume of 100 liters. Assume standard (STP) conditions.
Determine the following:
Mass percentage of the solution for the customer in the hospital
Molarity for the customer in the chemistry lab
Molality for the customer of the physics lab
2. A researcher is often required to prepare solutions in the lab. Typically, a lab provides a concentrated
solution. This solution must be diluted to the proper concentration. Hydrochloric acid is a common
stock solution that is typically purchased at 37.0% HCl concentration (density = 1.20 g/ml). You must
make 100 ml of 0.25 M HCl to do a DNA extraction experiment. How much of the 37.0% HCl
concentration stock do you need to prepare this solution?
3. The Haber–Bosch process for fixation of nitrogen is one of the more important chemical reactions
ever invented. Without the invention of this process, which is used to make ammonia for fertilizer, the
world’s population would not be as large as it is today.
N2(g) + 3H2(g) ? 2NH3(g)
List three ways in which the yield of ammonia in the reaction above can be improved for a given
amount of H2.
Additionally, explain the principle behind each method.

Copyright © 2013 by University of Phoenix. All rights reserved.