Preparation of Salts

Which of the following are important points of consideration for the precipitation method?

• Cation and anion of the desired product should be present

• The final product is to be insoluble

• The solubility of the starting reagents

• The same amount of each substance used

• CD is added continuously until no more change is observed in the beaker containing AB.

• Filter the mixture and collect the filtrate to use for crystallisation

• Wash the salt collected with distilled water

Why do we need to rinse the insoluble salt with distilled water?

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What are some of the important points that needs to be considered when selecting the titration method?

• Solubility of the final product

• Possible presence of unwanted side products

• Types of solution used

• Type of indicator used

Why is there a colour change at the end point?

What does "end point" mean?

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What affects the choice of the indicator?

• The steepness of the pH curve

• The point at which the pH change occurs

• The type of acid used

• The type of base used

Which of the following are steps taken to obtain a crystalline solid through the titration method?

• Titrate the acid against the alkali until the colour change is observed

• Repeat the titration once more without the indicator

• Heat the solution obtained from the titration without an indicator till solids form

• Filter the mixture and collect the crystals

Why do we use crystallisation and not evaporation to dryness?

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Answer explanation

We do not use heating to dryness as the salt may be thermally unstable and decompose at high temperatures.

What are some points that we need to consider when selecting the "Excess Insoluble Substance to Acid" Method?

• Presence of side products

• Solubility of the desired product

• Solubility of starting reagent

• Safety of the reaction