Mixing and Separating

A mixture is two or more substances combined together. In a mixture, each substance keeps its own properties. You can usually separate a mixture back into its parts. Trail mix is a mixture because you can pick out the nuts, raisins, and chocolate pieces one by one.

Types of Mixtures

Some mixtures are easy to see. A salad is a mixture where you can see all the parts. Other mixtures look the same throughout, like salt water or lemonade. These are called solutions. Milk looks smooth but is actually a mixture of water, fats, and proteins.

Separating Mixtures

Scientists use different methods to separate mixtures. Filtering catches big pieces and lets liquid pass through. Evaporation removes water and leaves dissolved solids behind. Magnets can separate iron pieces from other materials. Settling lets heavy parts sink to the bottom so lighter parts can be poured off.

Fun Facts

• Your blood is a mixture of red blood cells, white blood cells, platelets, and plasma.
• Water treatment plants use filtering, settling, and chemicals to separate dirt and germs from drinking water.
• Oil and water do not mix because water molecules attract each other more than they attract oil molecules.

Did You Know?

Gold miners in the old days separated gold from sand and gravel by panning. They swirled water and sediment in a pan. The heavy gold sank to the bottom while the lighter sand washed away!