Particles you can see

The idea

A suspension is a heterogeneous mixture in which solid particles remain undissolved and suspended throughout the medium; its particles are larger than those in a solution and visible to the naked eye.

Stirring a glass

You stir sugar into water: nothing can be seen. You stir sand into another glass: tiny grains are everywhere.

What is different about the sand?

• Its particles do not dissolve and are big enough to see
• Sand dissolves, like sugar
• Sand has no particles

Stir four solids into water

Stir sugar, then sand, sawdust and tea leaves into water. Compare what you can see.

Suspension

A suspension is a heterogeneous mixture in which solid particles do not dissolve but remain suspended throughout the bulk of the medium. The particles are larger than those in a solution and visible to the naked eye.

Examples: sand in water, sawdust in water, tea leaves in water.

Notes

A suspension is a heterogeneous mixture: undissolved solid particles, larger than a solute’s and visible, stay suspended in the medium.

Check yourself

Which of these is a suspension?

Compared with a solution, the particles of a suspension are…

In a suspension, the solid particles…

Tea leaves stirred in water form a…

• Sugar stirred into water. Sugar dissolves into a solution.
• Salt stirred into water. Salt dissolves into a solution.
• Sawdust stirred into water — correct. Yes. The particles are visible and do not dissolve.
• larger and visible to the naked eye — correct. Yes.
• smaller and invisible. Solute particles are the smaller ones.
• exactly the same size. Suspension particles are larger.
• dissolve completely. Then it would be a solution.
• turn into a gas. They remain solid particles.
• do not dissolve, but stay suspended in the medium — correct. Yes.
• solution, a homogeneous mixture. The leaves do not dissolve.
• suspension, a heterogeneous mixture — correct. Yes.
• pure substance. It is a mixture.