Salt Flashcards
1
Q
Methods of preparation of salt
A
- Reacting dilute acid with excess solid base/carbonate/metal (for all soluble salts except Group 1 metals)
- Titration (SPA salts)
- Precipitation (For insoluble salts)
2
Q
Reacting dilute acid with excess solid reactants
A
- Acid + excess metal -> salt + hydrogen
- Acid + excess insoluble base -> soluble salt + water
- Acid + excess insoluble metal carbonate -> soluble salt + carbon dioxide + water
3
Q
Why is reacting acid with excess metal not recommended?
A
The product, hydrogen gas is highly combustible.
4
Q
Why don’t we use excess acid?
A
Both acid and the salt formed are in the aqueous state and impossible to separate.
5
Q
Why is evaporation to dryness not used?
A
Most salts decompose on evaporation to dryness as they are not thermally stable. Hydrated salts will lose their water of crystallisation and form anhydrous salts, soluble impurities will also remain on the salt obtained.
6
Q
Why does reactants in titration must be in exact amount?
A
Excess of either reactants cannot be removed easily.
