Removing water of crystallisation in Acids, Bases and Salts – Class 10 Science Experiment

Chapter Name: Acids, Bases and Salts

Activity Name: Removing water of crystallisation in Acids, Bases and Salts

Activity Description:

Removing water of crystallisation in Acids, Bases and Salts - Class 10 Science Experiment

In this experiment, we will remove the water of crystallisation from copper sulphate crystals by heating them in a dry test tube.

The purpose is to observe the changes in the color of copper sulphate due to the loss of water of crystallisation and then attempt to restore the original color by adding water back to the dehydrated copper sulphate.

Required Items:

  1. Dry test tube
  2. Copper sulphate crystals
  3. Heat source (Bunsen burner or any suitable heating apparatus)
  4. Dropper
  5. Water

Step by Step Procedure:

  1. Take a few crystals of copper sulphate and place them in a dry test tube.
  2. Heat the test tube containing the copper sulphate crystals. Observe the changes occurring during heating.
  3. Note the color change in the copper sulphate crystals after heating.

Experiment Observations:

  • Upon heating the copper sulphate crystals, their color changes from blue to white.
  • Water droplets may be noticed on the sides of the test tube during the heating process. These droplets are a result of the water of crystallisation being driven out of the copper sulphate crystals.
  • After heating, the copper sulphate crystals become anhydrous (without water) and appear white in color.
  • Upon adding 2-3 drops of water to the dehydrated copper sulphate crystals, the blue color of copper sulphate is restored, indicating the reformation of hydrated copper sulphate.

Precautions:

  1. Use a dry test tube and ensure it is clean before starting the experiment.
  2. Handle the test tube with caution while heating to avoid any accidents or burns.
  3. Perform the heating step in a well-ventilated area to avoid inhaling any fumes.

Lesson Learnt from Experiment:

This experiment demonstrates the concept of water of crystallisation and how it affects the appearance of certain crystals. Copper sulphate, when hydrated, appears blue due to the presence of water molecules within its crystal structure.

On heating, these water molecules are driven out, and the copper sulphate becomes anhydrous and turns white. The experiment also shows that adding water back to the anhydrous copper sulphate allows it to reabsorb the water molecules and regain its original blue color.

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