A helium balloon at 28 degrees Celsius has a volume of 1.8 L and a pressure of 102 kPa. What is the volume of the balloon when it rises into the atmosphere where the pressure is 85 kPa and the temperature is 4 degrees Celsius?

1 Answer
Meave60
May 5, 2018

The volume of the helium balloon will be #"2.0 L"#.

Explanation:

This is an example of the combined gas law:

#(P_1V_1)/T_1=(P_2V_2)/T_2#

Note: The temperature for gas laws must be in Kelvins, so the Celsius temperatures will have to be converted.

Known

#P_1="102 kPa"#

#V_1="1.8 L"#

#T_1="28"^@"C + 273.15"="301 K"#

#P_2="85 kPa"#

#T_2="4"^@"C + 273.15"="277 K"#

Unknown

#V_2#

Solution

Rearrange the equation to isolate #V_2#. Plug in the known values and solve.

#V_2=(P_1V_1T_2)/(T_1P_2)#

#V_2=(102color(red)cancel(color(black)("kPa"))xx1.8"L"xx277color(red)cancel(color(black)("K")))/(301color(red)cancel(color(black)("K"))xx85color(red)cancel(color(black)("kPa")))="2.0 L"# (rounded to two significant figures)

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