Water as a Solvent
Polar water dissolves ionic and polar substances.
About this topic
Water is called the universal solvent because its bent shape and polar bonds give it a strong dipole, so it dissolves many ionic and polar substances. Hydrogen bonding gives it a high boiling point, high specific heat, high surface tension and the unusual property that ice is less dense than liquid water.
When salt dissolves, the partial negative oxygen ends surround the sodium ions, and the partial positive hydrogen ends surround chloride ions, a process called hydration that releases energy and stabilises the ions. Water's high specific heat (4.18 J/g·°C) means oceans and lakes absorb large amounts of heat with only small temperature changes, which moderates climate. Cohesion and adhesion cause capillary action in plants. Because ice floats, lakes freeze from the top and aquatic life survives below.
Examples: sugar dissolves because it has many polar OH groups, but oil does not because it is nonpolar. Blood carries nutrients dissolved in water, and nearly all biochemical reactions happen in water. Pure water is also slightly ionised: H2O gives H+ and OH-, which defines pH.
A misconception is that water dissolves everything; nonpolar substances such as fats, wax and many plastics do not dissolve. Also, the polar molecules are still neutral overall, with partial charges only.
Key ideas
- Ions are surrounded by water molecules
- Hydration energy
- Universal solvent is a nickname
Quick check
Use cases: where Water as a Solvent helps
- Homework: review the key idea behind Water as a Solvent before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Water as a Solvent without notes.
- Visual learning: play with the interactive lab to see how Water as a Solvent changes when you adjust its inputs.
- Teaching a friend: explain Water as a Solvent in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Water as a Solvent?
Polar water dissolves ionic and polar substances.
What will I learn in Water as a Solvent?
Ions are surrounded by water molecules. Hydration energy. Universal solvent is a nickname.
Is Water as a Solvent part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Water as a Solvent lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Water as a Solvent?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.