Lesson 13: What Goes Up
Combined Gas Law
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Homework
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Lesson 13: What Goes Up
Pages 312-315
Exercises #1-7
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ChemCatalyst
A weather balloon is inflated with helium to a volume
of 125,000 L. When it is released, it rises high into
the atmosphere, where both the pressure and the
temperature are lower.
1. Explain why the balloon rises.
2. Will the balloon pop at a high altitude? Explain
your thinking.
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Key Question
What is the relationship among pressure, volume, and
temperature for a sample of gas?
Let’s look at the other equations for a flexible container.
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You will be able to:
• define the combined gas law
• solve gas law problems that involve changes in all
three of the variables, P, V, and T
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Going Up
What happens to air pressure with increasing
altitude?
What happens to air temperature with increasing
altitude?
PV
The Combined Gas Law is
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k=
T
Using the Gas Law formulas
Any time you can solve for k in a gas law, e.g.,
PV
k = ------T
That ratio becomes proportional to any other situation with
the same proportionality constant. In other words:
P 1V 1
---------- = k =
T1
or
P 1V 1
--------T1
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=
P 2V 2
-------T2
P 2V 2
--------T2
Sample Problem
Complete the temperature column on the table.
Sample problem: 5,000 ft (see worksheet #2)
Complete the worksheet. You MUST use units!
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