Size decides the mixture

The idea

Solutions, colloids and suspensions differ mainly in particle size: solute particles in a solution are smallest (less than 1 nm), colloid particles are 1–1000 nm, and suspension particles exceed 1000 nm in diameter.

Three kinds of mixture

Sugar in water, milk, and sand in water look very different. They differ mainly in one thing: how big the dissolved or suspended particles are.

Which mixture has the smallest particles?

• The solution
• The suspension
• The colloid

Slide the particle size

Slide the size along the ruler. When does a solution become a colloid, and a colloid a suspension?

Particle size

Solutions, colloids and suspensions differ mainly in particle size: solution less than 1 nm in diameter, colloid 1 to 1000 nm, suspension more than 1000 nm.

Unlike a suspension, the particles of a colloid do not settle over time.

Notes

Solution: less than 1 nm. Colloid: 1 to 1000 nm. Suspension: more than 1000 nm.

Check yourself

Particles of diameter 0.5 nm make a…

Particles of diameter 100 nm make a…

Particles of diameter 5000 nm make a…

Which order goes from the smallest particles to the largest?

• colloid. A colloid’s particles are 1 to 1000 nm.
• suspension. A suspension’s particles are above 1000 nm.
• solution — correct. Yes. Less than 1 nm.
• colloid — correct. Yes. Between 1 and 1000 nm.
• solution. A solution’s particles are less than 1 nm.
• suspension. A suspension’s particles are above 1000 nm.
• colloid. A colloid’s particles are at most 1000 nm.
• suspension — correct. Yes. More than 1000 nm.
• solution. A solution’s particles are less than 1 nm.
• suspension, colloid, solution. That is the reverse.
• colloid, solution, suspension. A solution’s particles are the smallest.
• solution, colloid, suspension — correct. Yes.