What is the correct order to separate a mixture of sand, water and ethanol? a. decantation, filtration b. decantation, distillation c. filtration, decantation d. distillation, solvent extraction
The correct answer and explanation is:
Correct Answer: b. decantation, distillation
To separate a mixture of sand, water, and ethanol, the most effective method involves decantation followed by distillation.
First, decantation is used to separate sand from the liquid components (ethanol and water). Sand is an insoluble solid that settles at the bottom of the container when left undisturbed. Carefully pouring off the top liquid layer while leaving the sand behind is called decantation. This step effectively removes most of the solid material without needing filtration.
Once the sand is removed, the remaining mixture consists of water and ethanol, which are both liquids and completely miscible. To separate these two, distillation is used. Distillation works by exploiting the difference in boiling points between the two liquids. Ethanol has a boiling point of about 78.5°C, while water boils at 100°C. When the mixture is heated, ethanol vaporizes first. These vapors are then condensed in a separate container, effectively separating ethanol from water.
This combination of techniques works well because:
- Decantation is a quick and simple method for removing heavy solid particles like sand.
- Distillation is the appropriate method for separating two miscible liquids based on boiling point differences.
Other options are less effective:
- Filtration (in option a and c) would also remove sand but is usually slower and can clog with fine particles.
- Solvent extraction (in option d) is unnecessary since water and ethanol are both polar and already form a single phase.
Therefore, the best sequence for separating sand, water, and ethanol is decantation to remove sand, followed by distillation to separate ethanol from water.