Question

1. State the Avogadro law. 

2. Give the mathematical expression of this law. 

3. What is the value of molar volume of an ideal gas at 273.15 K and 1 bar? 

4. Show that, at constant temperature and pressure, the density of an ideal gas is proportional to its molar volume.

Answer 1

1. It states that equal volumes of all gases under the same conditions of temperature and pressure contain equal number of molecules.

2. v ∝ n (at constant P and T) 

⇒ V = k × n where k is a proportionality constant..

3. 22.71098 L 

4. According to Avogadro law, for n moles of an ideal gas, 

V = k × n 

But n = \(\frac{m}{M}\) where m is the mass of the gas and M is its molar mass. 

Thus, V = k × \(\frac{m}{M}\) 

On rearranging the above equation, 

M = k × \(\frac{m}{V}\) = k × d 

⇒ M ∝ d