A solution of salt water sits in the sun for 6 days. after 6 days, only the salt remains in the cup. Explain why this is an example of a mixture.

1 Answer | Add Yours

t-nez's profile pic

t-nez | High School Teacher | (Level 3) Associate Educator

Posted on

Mixtures can be separated by physical means, while compounds can only change composition via a chemical reaction. Since the salt was separated by evaporation of the water without evidence of a chemical reaction we know that the salt water was a mixture. Evaporation, the process that removed the water from the salt, is a physical change.

Some other physical processes for separating mixtures are:

Distillation - separating liquids with different boiling points by boiling off each substance step-wise.

Magnetism - iron-containing particles can be separated out of a mixture using a magnet.

Screening - a screen can be used to separate substances that have particles of different sizes. 

An example of a compound (which is a pure substance) being separated by chemical means is the application of electric current to water to produce hydrogen and oxygen gases.

We’ve answered 318,994 questions. We can answer yours, too.

Ask a question