# 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

Jun 10, 2018

The partial pressure of $C {O}_{2}$ in this mixture is 2.72 atm.

#### Explanation:

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 $C {O}_{2}$ gas and the water vapour. To find the partial pressure that the $C {O}_{2}$ exerts is just a case of rearranging:

$\text{total pressure" = p(CO_2) + "vapour pressure of water}$
$2.76 = p \left(C {O}_{2}\right) + 0.039$
$p \left(C {O}_{2}\right) = 2.76 - 0.039$
$p \left(C {O}_{2}\right) = 2.721 a t m = 2.72$ (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).