Salt preparation by titration method

1. Salts Preparation
Preparation of Salts By Titration
LEARNER’s OUTCOMES
 Describe the process of titration to prepare salts
 Write chemical equations for reactions used in the
preparation of salts
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2. Salts Preparation – Recap
Precipitation Method
 Starting materials: 2 aqueous solutions
 Products: Insoluble salt and Soluble salt
 Eg: How do you prepare barium sulfate salt?
 barium nitrate + sodium sulfate  barium sulfate + sodium nitrate
Ba(NO3)2 (aq) + Na2SO4 (aq)  BaSO4 (s) + 2NaNO3 (aq)
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3. Salts Preparation
Can sodium chloride be prepared by
precipitation ?
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4. Salts Preparation – Recap
Salts
 A salt is formed when an acid is
neutralised by a base.
Acid + Base
 A salt contains two parts:
 Metal part : cation (comes from the
base)
 Non-metal part : anion (comes from
the acid)
Salt
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5. Salts Preparation
Method of preparing sodium chloride - Titration
Action of acid on alkali
ACID + ALKALI  SALT + WATER
 This process is called neutralisation.
 To carry out the neutralisation of the acid
and alkali exactly, a method called titration
is used.
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6. Salts Preparation - Titration
When do you choose Titration?
- Soluble salts that are:
• Group I metal salts i.e. sodium chloride, potassium nitrate, lithium
sulfate
• Ammonium salts i.e. ammonium chloride, ammonium sulfate
-Starting materials used must be an acid and an alkaline
-The salts listed in Table 1 can be prepared by the titration method.
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7. Salts Preparation - Titration
Examples of Salts Prepared by titration
Table 1
Base (alkali) Acid Salt
Sodium hydroxide Hydrochloric acid Sodium chloride
Potassium hydroxide Hydrochloric acid potassium chloride
Sodium hydroxide Sulphuric acid Sodium sulphate
Potassium hydroxide Sulphuric acid Potassium sulphate
Calcium hydroxide Nitric acid Calcium nitrate
Ammonia solution Nitric acid Ammonium nitrate
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8. Salts Preparation - Titration
1. Pipette 25.0cm3 of dilute
hydrochloric acid into a
conical flask
Dilute
2. Add 2-3 drops of hydrochloric
acid
phenolphthalein into the
conical flask
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9. Salts Preparation - Titration
3. Fill burette with sodium hydroxide and record the initial reading as V1 cm3
4. Titrate dilute hydrochloric acid with sodium hydroxide from the burette
slowly and swirl the solution until it starts to turn pale pink
5. Add sodium hydroxide dropwise till solution turn pale pink permanently. This
is the end-point of neutralisation.
6. Record the final burette reading as V2 cm3. Hence the volume of sodium
hydroxide required for complete neutralisation = (V2 -V1) cm3
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10. Salts Preparation - Titration
Burette
V1
V2
Sodium Hydroxide
Dilute Sodium chloride
hydrochloric and water
acid 10

11. Salts Preparation - Titration
7. Pipette 25.0cm3 of hydrochloric acid into another conical flask
8. Add (V2 -V1)cm3 of sodium hydroxide from the burette into conical flask
9. Heat the sodium chloride solution to evaporate the water till it is saturated
10. Allow saturated solution to cool for crystallization to take place
11. Filter to collect the sodium chloride crystals
12. Dry crystals between a few sheets of filter paper
Sodium chloride and
water
Sodium
chloride and
water
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12. Salts Preparation - Titration
Discuss how you can prepare ammonium nitrate crystals.
- what starting materials to use?
- chemical equation?
- percentage yield?
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