S3 Salts Flashcards
What are the use of salts around us?(3)
Table salt, fertilisers, photography
Are all nitrates soluble?
Yes
Are all halides (grp VII) soluble?
Yes except lead and silver halides
Are all sodium, potassium and ammonium salts soluble?
Yes
Are all carbonates soluble?
No except sodium, potassium and ammonium carbonates.
Are all sulfates soluble?
Yes except Lead(II), calcium and barium(II) (lazy charlie brown)
Are all hydroxides soluble?
No except hydroxides of group I elements, ammonium and sparing calcium
Are all oxides soluble?
No except oxides of ammonium and group I elements
How do you prepare soluble salts by reacting with acids?
Reaction with acids and excess reactive metals, base and carbonate.
Why do you use excess reactive metal/base/carbonate when preparing soluble salts?
The acid will all be reacted due to the excess solid reactant used, and the excess solid reactant can easily be filtered out.
What is the general state equation for reactions with acids?
Aq + s = aq
When is titration needed with soluble salts?
If both starting reactants are soluble
Why is titration least preferred?
Titration is tedious because exact amount of reactants have to be added.
How to prepare insoluble salts with precipitation?
Select 2 soluble reactants that will react to form the salt. Since the salt is insoluble, it can easily be precipitated as a solid and purified by filtering and washing with distilled water.
What is the general state equation for precipitation?
aq+aq=s
Name the process of precipitation.
1) pour solution 1 to solution 2 to allow precipitation to take place.
2) filter the solution to obtain the insoluble salt as residue.
3) wash salt with distilled water to remove impurities.
4) dry the salt using filter paper.
What are anhydrous salts?
They do not exist as liquid state while hydrated salts do.
How to prepare soluble salts with excess reactive metal/base/carbonate?
Add excess reactive metal/base/carbonate to hot dilute acid and stir consistently until nothing else can dissolve. Remove the excess base by filtration. Heat the filtrate to evaporate most of the water and produce a saturated solution. Dip a clean dry glass rod in the solution to test for saturation. Allow the saturated solution to cool and crystals will be formed upon cooling. Filter the zinc sulfate crystals and wash with deionzed water. Dry them using filter paper.
How to prepare soluble salts with titration?
Pipette a fixed amount of acid into a clean conical flask. Add a few drops of an indicator, then fill a burette with the reactant. Add it few drops at a time, into the conical flask until the indicator changes color. Record the volume of reactant used, then repeat the experiment with the same volume of acid and reactant in a clean conical flask without any indicator. The solution is then placed in an evaporating dish and crystals of sodium sulfate are obtained by crystallisation.
What are the 6 reactive metals that can be used for acid reaction to form salt?
1) mg
2) Al
3) Zn
4) Fe
5) Sn
6) Pb
