To solve this problem, let us first assume that the hydrogen gas acts like an ideal gas. So that we can make use of the ideal gas equation:
P V = n R T
where P is the pressure, V is the volume, n is the number of moles, R is the universal gas constant and T is the absolute temperature
Since it is given that T and P is constant therefore we can write the equation as:
V / n = k
So equating the two conditions:
V1 / n1 = V2 / n2
We can now solve for the new V2 given n2 = 0.125:
2 L / 820 mol = V2 / 0.125 mol
V2 = 3.05 x 10^-4 L
The new volume is about 3.05 x 10^-4 L which is equivalent to 0.3 mL
