[arli21]

Hi!

I would like to determine the diffusion coefficient of tritiated water in regular water, and then in salt water (I don't know if the difference would be noticeable). What kind of experiment could I put into place? I have high-school level chemistry material

Thanks!

[Enthalpy]

Hi arli21,

Let's imagine that H and T atoms move in complete water molecules - I have no definite opinion about that. That's not obvious, and in acidic environment they would much jump as H⁺ and T⁺ from one molecule to an other, competing with the diffusion of complete water molecules. Whether NaCl offers some process similar to H₃O⁺, I don't know.

With macroscopic quantities, which are dangerous, you could just connect a contained of normal water with a container of tritiated water over a narrow pipe, avoid evaporation, and observe how the water density hence water levels change over time.

Or does "tritiated" mean a low concentration? Then you can observe the concentration over position and time by the radioactivity.

In case your tritiated water is T₂O, you will soon obtain twice as much HTO, and this will spoil your experiment. Measuring HTO would be simpler.

The diffusion coefficient should be close to the H₂O and HDO ones, so you can predict the approximate outcome and double-check it.

Avoiding turbulence is difficult, especially because water is runny - hence the narrow pipe. For instance at La Hague's outlet in the Ocean, turbulence decides everything and diffusion nothing.

Where do you find tritiated water? Significant quantities are regulated and monitored because tritium serves to boost plutonium bombs. Also, take care of your health.