1. Salts
Noadswood Science, 2012

2. Wednesday, April 26, 2017
Salts
To know what salts are

3. Salts Salts are extremely useful chemicals
There are many different salts which can be produced, and their uses are vary varied…
They are produced when a neutralisation reaction occurs
Acid
Alkali
Salt + Water

4. Making Salts
If the base dissolves in water just enough acid needs to be added to make a neutral solution followed by evaporation of the water
Larger crystals form if you evaporate the water slowly

5. Making Salts
Copper oxide, and other transition metal oxides or hydroxides, do not dissolve in water
If the base does not dissolve in water it must be added to the acid until no more will dissolve and there is some base left over (excess)
The mixture must then be filtered to remove the excess base, and evaporated to leave the salt behind…

6. Experiment
You are going to mix an acid (hydrochloric acid) and an alkali (potassium hydroxide) causing a neutralisation reaction
Potassium chloride is the salt produced
Acid + Alkali → Salt + Water
Hydrochloric acid + Potassium hydroxide → Potassium chloride + water

7. Experiment – Part I Add 25cm3 hydrochloric acid to a 100cm3 beaker
Add 2cm3 potassium hydroxide solution and stir
Measure the pH using UI paper
Repeat steps 2 and 3 until the mixture is no longer acidic
*Record how much alkali you had to add!

8. Experiment – Part II
Now add your mixture into an evaporating basin, and heat gently
Heat until there is about a third of the liquid left (do not let it boil dry, as it will spit hot crystals out)
Examine the salt found

9. What Salt? Different salts are produced from different acids
Hydrochloric acid makes a metal chloride
Sulphuric acid makes a metal sulphate
Nitric acid makes a metal nitrate
Phosphoric acid makes a metal phosphate

10. Naming Salts
The name of a salt has two parts. The first part comes from the metal in the base or carbonate, or the metal itself if a reactive metal like magnesium or zinc is used
The second part of the name comes from the acid used to make it. The names of salts made from hydrochloric acid end in -chloride, while the names of salts made from sulfuric acid end in -sulfate

11. Naming Salts Metal Acid Salt Sodium hydroxide Reacts with
Hydrochloric acid
To make
Sodium chloride
Copper oxide
Copper chloride
Sulfuric acid
Sodium sulfate
Zinc oxide
Zinc sulfate

12. State Symbols
State symbols describe the physical state something is in…
Solid (s)
Liquid (l)
Gas (g)
Aqueous – dissolved in water (aq)

13. Salt uses Salts can be put to many uses, including: -
Fertilisers (calcium phosphate & potassium nitrate)
Preservatives (sodium chloride)
Gun powder (potassium nitrate)
Varnish (copper sulphate)
Dye (copper sulphate)
Photographic film (silver nitrate)

14. Worksheet
Complete the worksheet about salts