Dispersion (chemistry) facts for kids

In chemistry, dispersion is a special kind of mixture. It's when tiny bits of one substance are spread out evenly through another substance. Think of it like glitter mixed into clear glue – the glitter bits are dispersed in the glue.

What is a Mixture?

A mixture is when two or more different substances are put together but don't chemically change into a new substance. You can often separate them again. For example, sand and water make a mixture. You can still see the sand, and you can separate it from the water.

How Dispersions are Different

In a dispersion, one substance is broken down into very small pieces. These pieces are then spread throughout another substance. The way these pieces are spread out makes dispersions unique. The size of these tiny pieces is very important for how we classify a dispersion.

Types of Dispersions

Scientists classify dispersions based on how big the tiny particles are. The three main types are solutions, colloids, and suspensions.

Solutions

Solutions are the most mixed-up type of dispersion. In a solution, the particles of one substance are so tiny that they completely dissolve in the other substance. You can't see the individual particles, even with a powerful microscope.

Examples of Solutions

• Salt water: When you stir salt into water, the salt crystals disappear. They break down into individual molecules that are too small to see.
• Air: The air we breathe is a solution of different gases. Nitrogen, oxygen, and other gases are mixed together perfectly.

Colloids

Colloids have particles that are bigger than those in solutions but smaller than those in suspensions. These particles are still very small, but they don't settle out quickly. They stay spread out for a long time.

Special Properties of Colloids

Colloids often look cloudy or opaque. They can also show something called the Tyndall effect. This means that if you shine a light beam through a colloid, you can see the path of the light. This happens because the particles are big enough to scatter the light.

Examples of Colloids

• Milk: Milk is a colloid where tiny fat droplets are dispersed in water. That's why milk looks white and not clear.
• Fog or clouds: These are colloids where tiny water droplets are dispersed in air.
• Jelly: This is a colloid where a solid (gelatin) is dispersed in a liquid (water).

Suspensions

Suspensions have the largest particles among the three types of dispersions. These particles are big enough that they will eventually settle to the bottom if left undisturbed. You can usually see the particles with your eyes.

How Suspensions Behave

Because the particles are larger, suspensions often look cloudy or muddy. If you let a suspension sit for a while, the particles will separate from the liquid. You can often filter suspensions to separate the parts.

Examples of Suspensions

• Muddy water: If you mix dirt with water, the dirt particles will eventually sink to the bottom.
• Orange juice with pulp: The pulp bits are suspended in the juice and will settle over time.
• Some medicines: Many liquid medicines are suspensions. That's why you need to shake them before using them.

Why is Dispersion Important?

Understanding dispersion is important in many areas of science and everyday life.

In Nature

• Blood: Our blood is a complex dispersion, with blood cells suspended in plasma.
• Soil: Soil is a dispersion of different mineral particles, water, and organic matter.

In Industry

• Paints: Paints are suspensions of tiny color pigments in a liquid.
• Cosmetics: Many lotions, creams, and makeup products are dispersions.
• Food products: Mayonnaise, salad dressings, and many drinks are examples of dispersions.

By knowing about dispersion, scientists and engineers can create new materials and improve existing products. It helps us understand how different substances mix and behave.

Images for kids

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  A robot, symbolizing technology and science where understanding dispersions is key.