Why is it necessary to run TLC in a closed container and to have the interior vapor saturated with the solvent? What error is introduced into the determination of an Rf value if the top is left off of the developing chamber?

See explanation

Explanation:

Rf value is known as retention factor.The retention factor of a particular material is the ratio of the distance the spot moved above the origin to the distance the solvent front moved above the origin(Harper College).

TLC is carried is out in a closed container and the interior is saturated with the solvent vapor in order to have a maximum resolution between components this prevents solvent from evaporating from the system.

Peradventure the solvent for the separation is partly or wholly  lost due to an open container, the Rf value would be lower than the expected value.

lol idk man i guess u gotta ask bill nye the science guy