The density of dichloromethane, an organic solvent, is 1.325g/cm3. If you mix 50 mL water and 50 mL dichloromethane together in a separatory funnel, which layer would be on top?
The correct answer and explanation is :
When mixing 50 mL of water and 50 mL of dichloromethane (DCM) in a separatory funnel, the water layer will be on top.
Here’s why:
- Density Comparison:
- The density of dichloromethane (DCM) is 1.325 g/cm³.
- The density of water is approximately 1.000 g/cm³ (at room temperature). In a two-liquid system like this, the layer with the higher density will sink, while the layer with the lower density will float. Since dichloromethane has a higher density than water, the dichloromethane will be the bottom layer, and water will be the top layer.
- Behavior in a Separatory Funnel:
A separatory funnel works on the principle of density differences. When immiscible liquids (liquids that do not mix, like water and dichloromethane) are added to the funnel, they form two distinct layers. The liquid with the greater density will occupy the bottom of the funnel, and the lighter liquid will float on top. - Layer Formation:
After mixing the two liquids in the separatory funnel, the two liquids will separate due to their different densities. The dichloromethane, being denser than water, will form the bottom layer, and the water will form the top layer. - Volume Considerations:
Even though we have equal volumes of each liquid (50 mL of water and 50 mL of dichloromethane), it is the density that dictates the layering. The mass of the dichloromethane will be greater because of its higher density, but the volume remains the same, so the dichloromethane will be the bottom layer.
Thus, after the liquids settle, you would observe water on top and dichloromethane at the bottom in the separatory funnel.