Chemistry Research Project - Salts

III. Method 2 – Neutralisation

• Used to prepare soluble salts
• Used when one of the reagents (can’t be the acid since all acids are soluble) is insoluble in water.
• When using excess metal we generally use moderately reactive metals such as Mg, Zn etc.

• Not unreactive metals such as Cu, Ag etc
• Not very reactive metals such as Na, K etc.

Method –

1. Add the metal, base or carbonate to the acid till it is in excess. In the case of carbonates and metals this can be ensured when the effervescence stops since CO2 and H2 are given out respectively.

• This ensures that all acid has been neutralised and thus it won’t contaminate the solution.

2. Filter off the excess base, metal or carbonate.
3. Heat the filtrate till the crystallisation point is reached. This can be checked for by dipping a glass rod into the solution. If it is saturated enough salt crystals would start forming around it.

• Don’t heat to dryness since then the water of crystallisation will be lost and proper crystals won’t form.

4. Let the saturated solution to cool slowly. Once crystals are formed dry them between pieces of filter paper.

IV. Method 3 – Titration

• To prepare a soluble salt
• Both the reagents are also soluble
• Especially useful for preparing Na, K etc. salts

Method –

1. Run a titration of the two reagents, one is in a conical flask, the other in a burette suspended above the conical flask.
2. Using an indicator determine how much base is required to neutralise the known amount of acid. Repeat 2 to 3 times.
3. Run the titration once again this time without the indicator using the same amount of base.
4. Heat the solution till the crystallisation point is reached. This can be checked for by dipping a glass rod into the solution. If it is saturated enough salt crystals would start forming around it.

• Don’t heat to dryness since then the water of crystallisation will be lost and proper crystals won’t form.

5. Let the saturated solution to cool slowly. Once crystals are formed dry them between pieces of filter paper.

V. List of salts

                   

VI. Commercial Uses of Salts

1. Ammonium Nitrate –

1. Used as fertiliser
2. Manufacture of explosives 
3. Manufacture of instant cool packs

2. Sodium Chloride –

1. Table Salt
2. De – icing roads 
3. Important component of drilling fluid

3. Copper(ii) Sulphate

1. Organic Synthesis
2. Copper Plating 
3. Etching zinc plates

4. Iron(ii) Sulphate

1. Treat Iron deficiencies
2. Manufacture of ink 
3. Used in horticulture

5. Zinc Sulphate

1. Treating zinc deficiencies
2. Treating acne 
3. Potential use as an alternative ADHD medication

Salt Preparation

Soluble Salt

Insoluble Salt

Precipitation

Soluble Reactants

Insoluble Reactants

Titration

Neutralisation

Examples

NaOH(aq) + HCl(aq) = NaCl(aq) + H2O(l)

NaOH(aq) + HNO3(aq) = NaNO3(aq) + H2O(l)

Examples

MgO(s) + H2SO4(aq) = MgSO4(aq) + H2O(l)

H2SO4(aq) + Zn(s) =  ZnSO4(aq) + H2(g)

Examples

KI(aq) + Pb(NO3)2(aq) = PbI2(s) + 2KNO3(aq)

Pb(NO3)2(aq) + H2SO4(aq) = PbSO4(s) + 2HNO3(aq)

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