The Universal Solvent

Why it matters

Drop a spoon of sugar into a glass of water and stir. It vanishes! Water can swallow up so many things that scientists gave it a special nickname.

Predict first

Why do people call water the universal solvent?

Water dissolves a huge variety of substances, more than most other liquids, so it is called the universal solvent. But it still cannot dissolve everything, like oil or sand.

• Because water can dissolve every single thing in the universe
• Because water dissolves more different substances than almost any other liquid — correct
• Because the universe is made only of water
• Because water is found only in outer space

What you do

Sort each substance into the correct bin: does it dissolve in water, or not?

Check yourself

Water can dissolve such a large number of substances that it is given a special name. What is it?

Water dissolves a very large variety of substances, so it is called the universal solvent. The substance that dissolves in it is the solute.

When salt fully dissolves in water, the salty water looks the same everywhere in the glass. What do we call such a mixture?

A solution is a homogeneous mixture: the solute spreads out evenly so the mixture looks exactly the same throughout.

You shake cooking oil with water, but the oil floats back to the top and refuses to mix. Why?

Oil and water are immiscible, meaning they do not mix. The oil stays separate and floats on top because it is lighter than water.

• The universal solvent — correct
• The universal solute
• The universal mixture
• The universal element
• A homogeneous solution — correct
• A suspension
• A heterogeneous mixture
• A pure substance
• Oil is immiscible with water, so it does not dissolve or mix in — correct
• Oil dissolves in water but only when it is cold
• Oil is heavier than water so it sinks
• Oil turns into a gas in water