Application of Avogadro’s Hypothesis:-
i] To establish the relation between molecular weight and vapour density or,
Prove that: Molecular Weight = 2 × Vapour Density
Mol. Wt. = 2 × V.D.
ii] Elementary Gases are diatomic gases
a] Hydrogen is a diatomic gas.
Applying Avogadro’s Hypothesis
n molecules n molecules 2n molecules
1 molecule 1 molecule 2 molecules
1/2 molecule 1/2 molecule 1 molecule
Thus,
1/2 molecule of hydrogen = 1 atom of hydrogen
1 molecule of hydrogen = 2 atoms of hydrogen
Hence, Hydrogen is a diatomic gas.
b] Chlorine is a diatomic gas.
Applying Avogadro’s Hypothesis
n molecules n molecules 2n molecules
1 molecule 1 molecule 2 molecules
1/2 molecule 1/2 molecule 1 molecule
Hence,
1/2 molecule of Chlorine = 1 atom of Chlorine
1 molecule of Chlorine = 2 atoms of Chlorine
Thus, Chlorine is a diatomic gas.
c] Nitrogen is a diatomic gas.
Applying Avogadro’s Hypothesis
n molecules n molecules 2n molecules
1 molecule 1 molecule 2 molecules
1/2 molecule 1/2 molecule 1 molecule
Hence,
1/2 molecule of nitrogen = 1 atom of nitrogen
1 molecule of nitrogen = 2 atoms of nitrogen
Thus, Nitrogen is a diatomic gas.
Applying Avogadro’s Hypothesis
n molecules n molecules 2n molecules
1 molecule 1 molecule 2 molecules
1/2 molecule 1/2 molecule 1 molecule
Hence,
1/2 molecule of oxygen = 1 atom of oxygen
1 molecule of oxygen = 2 atoms of oxygen
Thus, oxygen is a diatomic gas.
iii] Molar Volume of each gas at STP is 22.4 litre
According to application of Avogadro’s hypothesis
Molecular Weight = 2 × Vapour Density
or,