In a liquid-liquid extraction with dichloromethane and water, which statement is true?

In a liquid-liquid extraction involving dichloromethane (DCM) and water, the true statement is that dichloromethane will comprise the bottom layer. This is due to the density of the liquids involved. Dichloromethane is denser than water, with a density of approximately 1.33 g/cm³ compared to water's density of about 1.00 g/cm³.

When these two liquids are mixed, they do not form a homogeneous mixture; rather, they separate into two distinct layers due to their differing densities. In this case, the denser dichloromethane sinks and forms the bottom layer, while the less dense water floats on top. This behavior is fundamental in the principle of liquid-liquid extractions, allowing for the separation of compounds based on their solubility in different solvents.