Question

a balloon is filled with 25.7g of o2. the gas is at stp. calculate the volume of the O2 gas in liters.

Answer 1

At STP ,

pressure = P= 1 atm

Temperature = T= 273K

mass of O2 = 25.7 g

molar mass of O2 = 32.0g/mole

number of moles of O2 = mass/molar mass = 25.7/32.0 = 0.803 mole

number of moles of O2= n= 0.803 moles

Gas constant = R= 0.0821 L-atm/mol-K

Ideal gas equation

PV=nRT

V= nRT/P = 0.803 x 0.0821 x 273/1= 17.998 L

Volume of O2 gas = 18.0 L

(OR)

At STP

one mole of any gas occupies 22.4L of volume.

number of moles of O2= 0.803 moles

volume of one mole of O2 at STP = 22.4 L

volume of 0.803 moles of O2 = ?

                                                 = 22.4x0.803/1 = 17.98 L

Volume of O2 gas = 18.0L