Which description correctly differentiates a sol from a gel?

Which description correctly differentiates a sol from a gel?

• A. A gel is a solid dispersed in a liquid.
• B. A sol is a gas dispersed in a liquid.
• C. A sol is a colloid with solid particles in a liquid, while a gel is a liquid spread throughout a solid.
• D. A gel is a gas dispersed in a solid.

Answer: (D)

The key idea is how the dispersed phase and the continuous phase differ between sols and gels. In a sol, solid particles are dispersed through a liquid; the liquid is the continuous phase and the solid particles are the dispersed phase. This makes a cloudy mixture where the solid particles can move and flow within the liquid. In a gel, the situation is opposite: a liquid is trapped within a solid network. The solid forms a three-dimensional matrix that holds and immobilizes the liquid, so the dispersed phase is the liquid and the continuous phase is the solid. This gives a semi-solid, jelly-like substance. So, describing a sol as solid particles in a liquid and a gel as a liquid spread throughout a solid correctly captures the distinction. Descriptions that swap the phases—such as gas dispersed in a liquid, or liquid dispersed in a solid, or gas dispersed in a solid—don’t fit the standard definitions of sols and gels and describe different systems like foams or aerogels.

The key idea is how the dispersed phase and the continuous phase differ between sols and gels. In a sol, solid particles are dispersed through a liquid; the liquid is the continuous phase and the solid particles are the dispersed phase. This makes a cloudy mixture where the solid particles can move and flow within the liquid.

In a gel, the situation is opposite: a liquid is trapped within a solid network. The solid forms a three-dimensional matrix that holds and immobilizes the liquid, so the dispersed phase is the liquid and the continuous phase is the solid. This gives a semi-solid, jelly-like substance.

So, describing a sol as solid particles in a liquid and a gel as a liquid spread throughout a solid correctly captures the distinction. Descriptions that swap the phases—such as gas dispersed in a liquid, or liquid dispersed in a solid, or gas dispersed in a solid—don’t fit the standard definitions of sols and gels and describe different systems like foams or aerogels.