Which method is used to separate a solid from a liquid by filtering, such as sand from water?

Which method is used to separate a solid from a liquid by filtering, such as sand from water?

• A. Distillation
• B. Chromatography
• C. Crystallization
• D. Filtration

Answer: (D)

Filtration separates a solid from a liquid by using a porous barrier that traps the solid while letting the liquid pass through. In the sand-and-water example, the sand grains are too big to pass through the filter, while water molecules are small enough to go through the pores. As a result, the liquid becomes filtrate and the solid sand stays on the filter as residue. This method is ideal whenever the solid is insoluble or when you simply want to remove solids from a liquid without changing the liquid’s identity. Other techniques work differently: distillation relies on boiling and condensing to separate components by volatility, crystallization forms solids from a supersaturated solution as crystals, and chromatography separates components based on how they interact with a stationary phase. Filtration directly accomplishes the solid–liquid separation in a straightforward, physical way.

Filtration separates a solid from a liquid by using a porous barrier that traps the solid while letting the liquid pass through. In the sand-and-water example, the sand grains are too big to pass through the filter, while water molecules are small enough to go through the pores. As a result, the liquid becomes filtrate and the solid sand stays on the filter as residue. This method is ideal whenever the solid is insoluble or when you simply want to remove solids from a liquid without changing the liquid’s identity. Other techniques work differently: distillation relies on boiling and condensing to separate components by volatility, crystallization forms solids from a supersaturated solution as crystals, and chromatography separates components based on how they interact with a stationary phase. Filtration directly accomplishes the solid–liquid separation in a straightforward, physical way.