Ncert Exercises & Solutions

Calculate the number of degrees of freedom of molecules of hydrogen in 1 cc of hydrogen gas at NTP.

Hint: The degrees of freedom depends on the type of molecules.

Step 1: Find the no. of molecules.

The volume occupied by 1 mole = 1 mole of the gas at NTP = 22400 mL = 22400 cc

The number of molecules in 1 cc of hydrogen

= \frac{6.023 \times 10^{23}}{22400} = 2.688 \times 10^{19}

Step 2: Find the degrees of freedom of hydrogen molecules.

H_{2}

is a diatomic gas having a total of 5 degrees of freedom; 3 translational and 2 rotational.

∴

Total degrees of freedom possessed by all the molecules

= 5 \times 2.688 \times 10^{19}

= 1344 \times 10^{20}