The diagram below shows a separating funnel containing water and either dichloromethane or diethyl ether. At 20°C, the density of water is 1 g/mL, dichloromethane 1.33g/mL and diethyl ether 0.71g/mL. By considering the relative densities of the three solvents, the lower layer in the separating funnel is A. dichloromethane B. diethyl ether Type either A or B as your answer. -water
The Correct Answer and Explanation is:
Correct Answer: A
To determine which solvent forms the lower layer in a separating funnel, we compare the densities of the liquids. In a separating funnel, the denser liquid always settles at the bottom, while the less dense liquid floats on top.
Here are the densities at 20°C:
- Water: 1.00 g/mL
- Dichloromethane: 1.33 g/mL
- Diethyl ether: 0.71 g/mL
When a mixture of water and dichloromethane is placed in a separating funnel:
- Dichloromethane is denser than water (1.33 g/mL vs. 1.00 g/mL).
- Therefore, dichloromethane will form the lower layer.
- Water, being less dense, will form the upper layer.
On the other hand, if the mixture is water and diethyl ether:
- Diethyl ether has a lower density than water (0.71 g/mL vs. 1.00 g/mL).
- This means diethyl ether will float on top.
- Water will form the bottom layer in this case.
Since the question asks which one forms the lower layer in the separating funnel, we are looking for the solvent that is denser than water.
Only dichloromethane has a density greater than water, so it will sink and form the lower layer.
Conclusion:
When considering the relative densities of water, dichloromethane, and diethyl ether, dichloromethane is the heaviest and will occupy the bottom layer in the funnel. This is a key property used in liquid-liquid extractions during organic chemistry experiments, allowing efficient separation of two immiscible layers. Thus, the correct answer is:
A. dichloromethane.
