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?

Respuesta :

Answer:

0.178 moles of oxygen gas molecules were collected.

Explanation:

Pressure at which oxygen gas collected = p= 1.00 atm

Vapor pressure of the water [tex]p'=34.5 Torr=\frac{34.5}{760} atm=0.0454 atm[/tex]

Pressure of the oxygen gas = P

p = p' + P

[tex]1.00 atm =0.0454 atm+P[/tex]

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 = [tex]25^oC=273+25=298 K[/tex]

[tex]PV=nRT[/tex] (ideal gas)

[tex]n=\frac{PV}{RT}=\frac{0.9546 atm\times 4.56 L}{0.0821 atm L/mol K\times 298 K}=0.178 mol[/tex]

0.178 moles of oxygen gas molecules were collected.