How do you purify insoluble salt?

Purifying an insoluble salt involves a process of separating it from other soluble impurities and then drying it. Here's a breakdown of the steps:

Steps to Purify Insoluble Salt

The process for purifying insoluble salts, as described in the reference, focuses on separating the insoluble salt from other soluble impurities and ensuring it's clean and dry. The procedure can be summarized as follows:

1. Dissolving Soluble Impurities:

   • The reference mentions dissolving soluble salts. In the context of purifying an insoluble salt, this step involves using water to dissolve any soluble impurities that might be mixed with it. These impurities will then go into solution, leaving the insoluble salt undissolved.
   • Place the mixture containing your insoluble salt in a beaker with sufficient water.
   • Mix the contents well with a stirring rod to ensure the soluble impurities are completely dissolved into the water.

2. Filtering the Mixture:

   • The next step, according to the reference, is to "filter to remove precipitate from mixture." In the case of purifying an insoluble salt, the "precipitate" is your desired insoluble salt, which is now separated from the soluble impurities, which are dissolved in the water.
   • Use a filter paper and funnel to separate the solid insoluble salt (your precipitate) from the liquid solution containing the dissolved impurities (the filtrate).

3. Washing the Insoluble Salt:

   • The reference indicates washing the filtrate. However, in this context, the filtrate contains unwanted impurities. So, to purify the insoluble salt, we need to wash the salt remaining on the filter paper. The reference also specifies washing with "distilled water to remove traces of other solutions".
   • Wash the insoluble salt with distilled water while it remains on the filter paper. This removes any remaining soluble impurities that might be clinging to the salt crystals.

4. Drying:

   • The final step, as suggested by the reference is to "leave in an oven to dry."
   • Carefully remove the filter paper with the washed insoluble salt and leave it in a warm oven. This process will evaporate the water, leaving you with pure, dry, insoluble salt.

Key Takeaways

• The core principle here is the separation based on solubility: soluble substances are dissolved and removed, leaving the insoluble substance behind.
• The washing step is vital to ensure all traces of soluble impurities are completely washed away.
• The drying process completes the purification, resulting in a pure insoluble salt.