Question

calculate the ratio of the number of molecules in 2 litres of Oxygen and 8 litres of Nitrogen at stp

Answer 1

One mole of any gas occupies about 22.4 liters of space at STP.
Also, I mole contains Avogadro's number of molecules.
So, one mole of NH3 occupies 22.4 liters and has 6.022 × 10^23 molecules.
Therefore 1 liter contains 1 ÷ 22.4 moles.
Thus:
10 liters contain 10 ÷ 22.4 moles.
Therefore :
10 liters contain about 0.446 moles of NH3.
Now for number of molecules:
1 mole of NH3 contains 6.022 × 10^23 molecules.
Thus 0.446 moles of NH3 contain 6.022 × 10^23 × 0.446 molecules
= 2.6851 × 10^23 molecules.
Multiply by 4 for number of atoms.
This gives final answer:
2.6851 × 4 × 10^23 ATOMS.