Solubility Curves
Graphs show how much dissolves at each temperature.
About this topic
A solubility curve is a graph of how many grams of solute dissolve in 100 g of water at different temperatures. Points on the line are saturated, points below are unsaturated and points above represent supersaturated solutions. Most solids have curves that rise with temperature, such as potassium nitrate, whereas the curve for sodium chloride is almost flat and gases slope downward.
Reading the graph lets you predict how much solute will dissolve or crystallise. For example, if potassium nitrate has a solubility of about 110 g per 100 g of water at 60 degrees Celsius and 30 g at 20 degrees, cooling a saturated solution from 60 to 20 would cause roughly 80 g to crystallise out for every 100 g of water. Curves also show which substance is most soluble at a given temperature and compare multiple substances.
This principle is used in recrystallisation, a way to purify solids: dissolve in hot solvent, filter off insoluble impurities, then cool to let pure crystals form while impurities stay dissolved. Sugar and salt industries and drug makers use it. Rock candy is grown from a cooled sugar solution.
Common errors are reading the wrong axis, forgetting that values are per 100 g of water rather than per solution, and treating the line as sharp for gases. Below the line means more solute could be added; above it, the excess will not stay dissolved unless supersaturated.
Key ideas
- Most solids dissolve more when hot
- Gases dissolve less when hot
- A point above the curve is supersaturated
Quick check
Use cases: where Solubility Curves helps
- Homework: review the key idea behind Solubility Curves before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Solubility Curves without notes.
- Visual learning: play with the interactive lab to see how Solubility Curves changes when you adjust its inputs.
- Teaching a friend: explain Solubility Curves 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 Solubility Curves?
Graphs show how much dissolves at each temperature.
What will I learn in Solubility Curves?
Most solids dissolve more when hot. Gases dissolve less when hot. A point above the curve is supersaturated.
Is Solubility Curves 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 Solubility Curves 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 Solubility Curves?
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.