Question

a sample of O2 of volume 4.56 L was collected over water at 25c and a total pressure of 1.00 atm. The partial pressure of water is 34.5 Torr. How many moles of O2molescules were collected?

Answer 1

0.178 moles of oxygen gas molecules were collected.

Step-by-step explanation:

Pressure at which oxygen gas collected = p= 1.00 atm

Vapor pressure of the water
`p'=34.5 Torr=(34.5)/(760) atm=0.0454 atm`

Pressure of the oxygen gas = P

p = p' + P

`1.00 atm =0.0454 atm+P`

P = 1.00 atm - 0.0454 atm = 0.9546 atm

Volume of the oxygen gas = V = 4.56 L

Moles of oxygen gas = n

Temperature at which gas collected = T =
`25^oC=273+25=298 K`

`PV=nRT` (ideal gas)

`n=(PV)/(RT)=(0.9546 atm* 4.56 L)/(0.0821 atm L/mol K* 298 K)=0.178 mol`

0.178 moles of oxygen gas molecules were collected.