6.3 Preparation, Separation, and Purification of Soluble Salts
Soluble salts can be prepared through various methods, depending on the nature of the reactants involved. Here, we'll describe four common methods: reaction of acids with alkali (titration), excess metal, excess insoluble base, and excess insoluble carbonate.
6.3.1 Preparation by Titration (Acid and Alkali)
Activity 6.1
Preparation of sodium chloride (NaCl) from hydrochloric acid (HCl) and sodium hydroxide (NaOH) by titration.
Materials required
Dilute solutions of sodium hydroxide and hydrochloric acid. Phenolphthalein indicator Burette Pipette Conical flask Funnel Evaporating disc Burette stand, tripod stand, and heating source.
Procedure
Measure exactly of HCl solution using a pipette and transfer it to a conical flask. Add a few drops of phenolphthalein as an indicator to the acid. Fill a burette with NaOH solution using a funnel. Slowly add the NaOH from the burette to the HCl in the conical flask, swirling the flask continuously until the indicator changes colour from colourless to light pink indicating neutralization is complete.
Separation
Once the endpoint is reached, indicating that the acid and alkali have completely reacted, note the volume of NaOH used.
Crystallization
Evaporate the water from the resulting NaCl solution gently to obtain a hot saturated solution. Allow the solution to cool and crystallize, then filter to collect the crystals.