Preparing soluble salts
Solubility rules
| Salt type | Rule |
|---|---|
| sodium, potassium, ammonium | all soluble |
| nitrates | all soluble |
| chlorides | soluble, except lead and silver |
| sulfates | soluble, except barium, calcium, lead |
| carbonates | insoluble, except Na, K, ammonium |
| hydroxides | insoluble, except Na, K, ammonium (Ca partly) |
Practice
Which group of salts is always soluble?
All nitrates are soluble, as are all sodium, potassium and ammonium salts.
Making a soluble salt
- React an acid with:
- an alkali, using titration (both are solutions — measure exact volumes), or
- an excess of a metal, insoluble base, or insoluble carbonate.
- With an excess solid: filter off the leftover, then evaporate and crystallise.
Practice
To make a soluble salt from an acid and an alkali, you use:
Both are solutions, so titration measures the exact volumes that react.
Practice
Order the steps for making a soluble salt from an acid and excess solid.
React with excess → filter → evaporate → crystallise.
You've got it
Key idea
- learn the solubility rules (all Na/K/ammonium and all nitrates are soluble)
- soluble salt from an alkali → titration; from a solid → react with excess, then filter
- finish by evaporate + crystallise