Question

A gas cylinder contains 24 x 10 to the power of 24 molecules of nitrogen gas. If avogadros number is 6 x 10 to the power of 23 and the relative atomic mass of nitrogen is 14, calculate: i) Mass of nitrogen gas in cylinder. ii) Volume of nitrogen at STP in cubic decimetre.

Answer 1

there are 24x10^24 molecules of nitrogen.
Avogadro number denotes 1 mole of anything, usually molecules, atoms in an amount of substance, where 1 mole is 6x10^23 constituents.
here, we have to find out no. of moles of the nitrogen molecules
dividing the no. of molecules of nitrogen gas by the avogadro number
, we will find out the number of moles of the nitrogen gas.
calculating, the no. of moles is 40.
next, by formula, no. of moles= mass of the substance/ molecular mass of the substance
we know, the molecular mass of a substance is the atomic mass of the constituent atom of the molecule multiplied by the number of atoms in the molecule.
in the case of N2 gas, there are 2 nitrogen atoms in the same molecule.
since the atomic mass of nitrogen atom is 14(well, approximately), to find out the molecular mass of the molecule, we have to multiply 14 with 2.
molecular mass of nitrogen gas is 28.
the mass of the gas in cylinder is, then, to be found out by multiplying the moles of the gas with its molecular mass.
one mole of an ideal gas will occupy 22.4 litres at STP. To find out the volume of the gas in the cylinder in litres, multiply 22.4 litres with the number of moles in the cylinder.
ask if you still have doubts about anything..