O Level Chemistry – Questions on Salt Preparation

Salt Preparation is a topic that quite a few students are weak in. In order to successfully attempt any question on salt preparation, one has to be familiar with the following:-

1. Solubility table
2. Methods of preparation

In general, when one is posed with a salt preparation question, he needs to have the following train of thought:

1. Is the salt soluble? (knowledge of solubility table)
2. If soluble –> is it a SPA/Group I salt? If yes –> acid/alkali titration; if NO –> acid + excess method.
   If not soluble –> ionic precipitation method

Let’s take a quick look at how we can apply this knowledge to answering questions.

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Question

Briefly describe how sodium sulfate can be prepared in the lab.

Answer:

1. Is the salt soluble? (Yes! All Sodium Potassium and Ammonium salts are soluble!)
2. Is it a SPA salt? (Yes!)
3. Acid + alkali titration.
4. We will use sulfuric acid because we wish to obtain a sulfate salt. (We use HCl if we want to get a chloride salt and HNO3 if we want to get a nitrate salt.)
   We will use sodium hydroxide as the alkali.
5. Briefly describe the titration method!

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I hope this short post has helped you clear some doubts about salt preparation. If you found it useful, feel free to share this with your friends!