Lesson 2 of 6 · Solutions
Solubility and Temperature
🧂
🎯 Your mission
Set it up. Test it. Be amazed.
⚡ The twist
If it bubbles, something invisible is escaping.
What you'll learn
Most solids dissolve better in hot solvent, because faster particles break the lattice apart more readily. Gases do the opposite — they dissolve better cold, which is why a warm fizzy drink goes flat quickly and why warm rivers hold less oxygen.
Key words
solubility
The maximum mass of solute that dissolves in a given volume of solvent at a stated temperature.
saturated solution
A solution holding the maximum solute it can at that temperature.
Make a hypothesis first
Guess: will the fizz be loud, soft, or none at all?
Say your guess out loud — then find out if you were right.
Get ready
🧰 What you need
- potassium nitrate
- water bath
- thermometer
- balance
- boiling tubes
- stirring rod
- graph paper
Get ready
⚠️ Safety first
- Hot water and hot glassware scald — use a rack and tongs, never bare hands.
- Potassium nitrate is an oxidiser: keep it well away from paper and flames.
Step 1 of 4 · Read
Think about what you just learned: say what "solubility" and "saturated solution" mean in your own words before you start.
Step 2 of 4 · Do
Find the mass of potassium nitrate that just dissolves in 25 cm³ of water at five temperatures from 20 °C to 70 °C. Plot a solubility curve and use it to predict solubility at 45 °C.
Step 3 of 4 · Observe
Record what actually happened, including anything that did not match what you expected.
Step 4 of 4 · Record
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Question 1 of 2
Question 2 of 2
Mind = blown
🧪 If you could remove all the empty space from atoms, the entire human race would fit in a sugar cube.
Nice work!
You got 0 of 2 right.
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✨ More to explore
🌍 Where you see this in real life: This is happening in your kitchen right now — every time food cooks.
🏆 Stretch challenge (try it this week): Find one ingredient in a snack and look up what it does.
👨👩👧 For the dinner table: “What's something we cook that mixes things together this way?”
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Ready?
Solubility and Temperature
Set it up. Test it. Be amazed.
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