Question

How many moles of helium gas are contained in a 4.0-L flask at STP?

Answer 1

0.1784 moles of helium gas are contained in a 4.0-L flask at STP.

Step-by-step explanation:

At STP. temperature of the helium gas = T = 273.15 K

At STP, pressure of the helium gas = P = 1 atm

Volume of the helium gas at STP = V = 4.0 L

Moles of the helium gas = n

Using an ideal gas equation :

`PV=nRT`

`n=(PV)/(RT)=(1 atm* 4.0 L)/(0.0821 atm L/mol K* 273.15 K)`

n = 0.1784 mol

0.1784 moles of helium gas are contained in a 4.0-L flask at STP.