A chemist did an experiment and mixed baking soda with vinegar. She collected CO2 in a balloon. But there was also water vapor in the balloon. If the total pressure of the gas collected was 2.76 atm and the temperature was 290C, what was pressure of CO2?

Gas collected? 29 degrees Celsius

1 Answer
Jun 10, 2018

The partial pressure of #CO_2# in this mixture is 2.72 atm.


The sum of all partial pressures within a closed system will always equal the total pressure.

In this system (the sealed balloon), there are only two components - the #CO_2# gas and the water vapour. To find the partial pressure that the #CO_2# exerts is just a case of rearranging:

#"total pressure" = p(CO_2) + "vapour pressure of water"#
# 2.76 = p(CO_2) + 0.039#
#p(CO_2) = 2.76 - 0.039#
#p(CO_2) = 2.721 atm = 2.72# (3 significant figures)

Note that in order to do this calculation, you will need to know the vapour pressure of water at 29 degrees (0.039).