Compare Solutions, Suspensions, and Colloids based on stability and particle size.

When classifying mixtures, scientists look at the size of the solute particles and how they behave over time. These properties determine whether a mixture is a True Solution, a Suspension, or a Colloid.

Comparison Table

Property	Solution	Colloid	Suspension
Particle Size	Extremely small ($< 1$ nm)	Intermediate ($1$ nm to $1000$ nm)	Large ($> 1000$ nm)
Stability	Very Stable: Particles do not settle down over time.	Stable: Particles do not settle down (remain suspended).	Unstable: Particles settle down when left undisturbed.
Appearance	Transparent and clear.	Translucent or cloudy.	Opaque or very cloudy.
Filterability	Cannot be separated by filtration.	Cannot be separated by ordinary filtration.	Can be separated by ordinary filtration.
Tyndall Effect	Does not show Tyndall effect.	Shows Tyndall effect clearly.	Shows Tyndall effect (until settled).

---

1. Particle Size: The Scale of Mixtures

The behavior of these mixtures is almost entirely dictated by the size of their particles:

• Solutions: The particles are at the molecular or ionic level. They are so small that they cannot be seen even with a high-power microscope.

• Colloids: The particles are larger than molecules but small enough to stay suspended by the constant "bombardment" of the solvent molecules (Brownian motion).

• Suspensions: The particles are large enough to be seen with the naked eye. They are heavy enough that gravity eventually pulls them to the bottom.

---

2. Stability: Will it stay mixed?

Stability refers to whether the solute stays evenly distributed or separates over time.

• Solutions (Stable): If you leave a glass of saltwater on a table for a week, the salt will not sink to the bottom. It remains perfectly dissolved.

• Colloids (Stable): Milk is a colloid. The fat globules don't sink to the bottom of the carton because they are small enough to stay "tossed around" by the water molecules.

• Suspensions (Unstable): Think of sand in water. If you stop stirring, the sand immediately begins to fall to the bottom. This makes it an unstable mixture.

---

Common Examples

• Solution: Sugar in water, Vinegar, Air.

• Colloid: Blood, Ink, Whipped cream, Fog.

• Suspension: Chalk powder in water, Muddy pond water, Paints.