Can isotopes be separated by chemical methods?

Answer 1

Since isotopes are nearly chemically identical, the use of chemical processes to separate isotopes is impractical, but it is used to separate deuterium from normal hydrogen. The extreme mass differences of deuterium and hydrogen (being twice its mass), allows for a more noticeable chemical difference: when chemical equilibrium is established with water (H2O or HDO, with one deuterium replacing the hydrogen) with pure light hydrogen gas, there is 3 to 4 times more deuterium in the liquid compound than in the gas. Thus, this difference can be used to separate the heavier deuterium from light hydrogen.

But the use of chemical methods would only work if the mass of the isotopes are immensely different, which only occurs with lighter elements.

To separate other isotopes, the physical properties of the compounds are used since they directly relate with the slight difference in masses.

The most common example of separation by physical properties is the separation by effusion, which is commonly used to separate uranium-235 (used in weapons and power generation) and uranium-238. These mass differences result in a different effusion rate as predicted by the Kinetic Molecular Theory, thus the lighter U-235 effuses faster than U-238, and the process being repeated many times nearly pure U-235 results.