The volume of a sample of hydrogen gas was decreased from 13.16 L to 6.45 L at constant temperature. If the final pressure exerted by the hydrogen gas sample was 7.73 atm, what pressure did the hydrogen gas exert before its volume was decreased?

1 Answer
Jacob T.
Apr 2, 2018

#3.79 " atm"#

Explanation:

Assuming ideal behavior, the gas sample should satisfy the Boyle's law, which states that
#"P"*"V"="a constant"#
when temperature is held constant. [1]

In other words, the pressure the gas exerts is inversely related to the volume of the airtight container.

Therefore
#"P"_1*"V"_1="P"_2*"V"_2#
#"P"_1=("P"_2*"V"_2)/("V"_1)="P"_2* ("V"_2)/("V"_1)#

Evaluate with #"V"_1=13.16" L"#, #"V"_2=6.45" L"#, #"P"_2=7.73" atm"# as given in the question:
#"P"_1=7.73" atm" * (6.45" "cancel("L"))/(13.16" "cancel("L"))=3.79" atm"#
(rounded to three significant figures)

Reference
[1] https://www.grc.nasa.gov/www/k-12/airplane/boyle.html

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