Question

Calculate the no. Of molecules of oxygen gas that occupies a volume of 224ml at 273k and 3 atm pressure

Answer 1

Using Boyle’s Law, P1V1 = P2V2,

224ml at 3 Atm is 3 x 224 = 1 x V2, so V2 = 672ml or 0.627L

We know from Avogadro’s Law that 1 mol of a gas occupies 22.4L at STP and contains 6.022 x 10^23 molecules.

Here, we have 0.627/22.4 = 0.028 mol, so that amount of moles contains 0.028 x 6.022 x 10^23 = 1.686 x 10^22 molecules