Suspension (chemistry) facts for kids

Flour in water forms a suspension

In chemistry, a suspension is a special kind of mixture. Imagine you mix two or more things together, but one of them doesn't completely dissolve. That's a suspension! It's like when you stir sand into water. The sand doesn't disappear; it just spreads out in the water.

In a suspension, tiny solid pieces are mixed into a liquid. But these solid pieces are too big to truly dissolve. If you leave a suspension still for a while, the solid parts will separate. They might sink to the bottom or float to the top. How fast they separate depends on what the suspension is made of.

What is a Suspension?

A suspension is a mix where small solid bits are spread throughout a liquid. Think of it like a cloudy drink. The solid particles are big enough that you can often see them. They are also big enough that gravity will pull them down (or sometimes push them up) if the mixture is left alone. This is different from a solution, where one substance completely dissolves into another, like sugar in water.

Examples of Suspensions

You can find suspensions all around you!

• Muddy water: This is a classic example. Dirt and soil particles are suspended in water. If you let it sit, the mud will settle at the bottom.
• Flour and water: When you mix flour into water for cooking, it forms a suspension. The flour doesn't dissolve, and it will eventually settle.
• Some medicines: Many liquid medicines, especially those you have to shake before using, are suspensions. The active ingredients are tiny solid particles suspended in a liquid. Shaking them makes sure you get the right amount of medicine.
• Paint: Paint is often a suspension of tiny solid color particles in a liquid. That's why you sometimes need to stir or shake paint before using it.

Other Types of Mixtures

Not all mixtures are suspensions. Here are a couple of other interesting types:

• Emulsion: If you mix two liquids that don't dissolve in each other, you get an emulsion. One liquid is spread out in tiny droplets within the other. A great example is milk. Milk is an emulsion of tiny fat droplets in water.
• Aerosol: When tiny liquid droplets or solid particles are spread out in a gas, it's called an aerosol. Fog or mist are good examples. They are made of tiny water droplets floating in the air.

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