Chemists study suspensions and solutions. What are they all about? Try this simple experiment and find out.
Things Required:
2 large wide-mouth jars, half-filled with water
2 tablespoonfuls of salt
2 tablespoonfuls of soil
A hand lens
Spoon
Directions:
Add the soil to one jar of water, the salt to the other. Stir both. Look through your hand lens at both jars.
This Is What Happens:
The particles of soil appear to be hanging in the water. Because of their weight, the larger soil particles settle to the bottom of the jar first, followed by the medium particles, and then the smaller ones. The particles of salt in the other jar have disappeared, or dissolved.
Science Behind It:
The soil did not dissolve, or mix and disappear, into the water, because soil and water are composed of the molecules of different types. These different molecules cannot chemically combine. Soil and water are what chemists call a “suspension” because the soil particles spread, or become suspended, throughout the water and then later settle to the bottom of the jar, or come out of suspension. But water and salt do combine. The salt dissolves, or seems to disappear, in the water. Its particles (crystals) do not fall to the bottom of the jar. This is an example of a solution. Chemists call the solid molecules that become part of a solution, such as salt, a “solute,” and the liquid molecules, such as water, a “solvent”.
