# Chloroform-acid wash

If I wash chloroform (stabilized with amylene) with sulphuric acid in a separating funnel, where will the chloroform be found (top or bottom)? I think the chloroform will be at the bottom, because it is heavier than sulphuric acid.

• Do you mean concentrated sulfuric acid or an aqueous dilution? – jerepierre Jul 14 '15 at 14:26

Usually, you shake chloroform with concentrated sulfuric acid, wash with water, dry over $\ce{CaCl2}$, and distill.

The density of chloroform is approximately $\rho = 1.48\ \mathrm{g\ cm^{-3}}$, whereas the density of concentrated sulfuric acid is approximately $\rho = 1.84\ \mathrm{g\ cm^{-3}}$. Therefore, after you allow the layers to separate, the concentrated sulfuric acid is in the lower layer and the chloroform is in the upper layer.

After that, however, when you wash with water ($\rho = 1.00\ \mathrm{g\ cm^{-3}}$), the chloroform is in the lower layer and the water is in the upper layer.

If there is any doubt about the identity of a layer, add a drop of the layer in question to a small amount of water in a test tube. If the drop does not dissolve, the layer in question is the organic layer.

Caution: The mixture may become hot when the remaining sulfuric acid is removed with water, and chloroform boils at $61.2\ \mathrm{^\circ C}$.

Pure, concentrated sulfuric acid has a density of 1.84 grams per cubic centimeter. Chloroform has a density of 1.489 grams per cubic centimeter. Thus a chloroform phase will form on top of a pure sulfuric acid phase.

However, if you are using dilute sulfuric acid, the density will be closer to that of water (1 gram per cubic centimeter), and chloroform may form beneath an aqueous acid phase.

There is a concentration of water in sulfuric acid at which the density of the aqueous acid phase will be equal to that of the chloroform. In that case, the layers will never separate (at least not vertically).