From the given equation, we have the general form of the equation of state for a real gas.
To find the mass of the gas, we use the ideal gas law for an approximation of molar mass.
The equation for pressure \( P \) is:
\[
P = \frac{RT}{2v-b} - \frac{a}{4v^2}
\]
where \( R \) is the gas constant, \( T \) is temperature, \( v \) is molar volume, and \( a \) and \( b \) are constants specific to the gas.
Using the ideal gas law approximation and solving for the mass, we find that the mass of the gas is \( 22 \, \text{g} \).
Thus, the correct answer is (b).