Two liters of a perfect gas are at 0>c and 1 atm. if the gas is nitrogen, n2, determine the number of molecules.

Solution;

The gas is at STP;

Where; T = 273 K, P = 1 atm

We know that 1 mole of a gas at STP occupies a volume of 22.4 liters.

V1/n1 = V2/n2

n2 = (V2/V1) n1

n2 = (2 l/22.4 l) (1 mole)

n2 = 0.0893 moles

But 1 mole of a compound has 6.022 * 10^23 molecules

Thus, number of molecules = 0.0893 moles * 6.022 * 10^23 molecules

= 5.378 * 10^22 molecules.