Question

A 2.00-L sample of was collected over water at a total pressure of 750. torr and 22 °C. When the was dried (water vapor removed), the gas had a volume of 1.95 L at 22 °C and 750. torr. Calculate the vapor pressure of water at 22 °C.

Answer 1

Answer : The vapor pressure of water at
`22^oC` is 1.01 atm.

Explanation :

Boyle's Law : It is defined as the pressure of the gas is inversely proportional to the volume of the gas at constant temperature and number of moles.

`P\propto (1)/(V)`

or,

`P_1V_1=P_2V_2`

where,

`P_1` = initial pressure = ?

`P_2` = final pressure = 750 torr = 0.987 atm (1 atm = 760 torr)

`V_1` = initial volume = 1.95 L

`V_2` = final volume = 2.00 L

Now put all the given values in the above equation, we get:

`P_1* 1.95L=0.987atm* 2.00L`

`P_1=1.01atm`

Therefore, the vapor pressure of water at
`22^oC` is 1.01 atm.