Question

5.6 litre of oxygen at stp contains how many atoms

Answer 1

22.4 litres of a gas indicates 1mole.
5.6 litres of the gas indicates 0.25 moles.

1mole of O₂ gas contains 2 x Avogadro number of atoms of oxygen.
so,
0.25 moles of O₂ contains →0.25 x 2 x Avogadro number of atoms of oxygen
                                          →0.5 x 6 x 10²³ oxygen atoms
                                          →3 x 10²³ oxygen atoms

∴ 5.6 litres of Oxygen gas contains 3 x 10²³ oxygen atoms.

Answer 2

5.6 litres of oxygen contains $3.0115$×$10^{23}$ atoms

Explanation:

• One mole of gas at NTP has a volume of 22.4 litre. It is known as the molar volume.
• The atomicity of oxygen is 2.
• Thus one mole of oxygen contains two times the number of oxygen molecules
• Thus 22.4 litres of oxygen contains $6.023$×$10^{23}$ molecules.

• 1 litre of oxygen will contain $6.023$×$10^{23}$×$22.4$ molecules

• 5.6 litres of oxygen contains $6.023$×$10^{23}$×$5.6$/$22.4$ molecules

• 5.6 litres of oxygen contains $1.50575$×$10^{23}$ molecules

• Therefore 5.6 litres of oxygen contains $1.50575$×$10^{23}$×$2$ atoms

• 5.6 litres of oxygen contains $3.0115$×$10^{23}$ atoms

Also we know that one mole of a gas contains avogadro number of molecules and it contains atoms equal to the product of number of molecules and atomicity .