Separation of mixtures by sublimation in Is Matter Pure – Class 9 Science Experiment
Chapter Name: Is Matter Pure
Activity Name: Separation of mixtures by sublimation in Is Matter Pure
Activity Description:
This experiment focuses on separating a mixture of common salt and ammonium chloride by sublimation, a process where a solid directly changes into vapor without becoming a liquid first.
Required Items:
- One tablespoon of common salt
- One tablespoon of ammonium chloride
- China dish
- Glass funnel
- Cotton
- Stove
- Stand for the stove
Step by Step Procedure:
- Take one tablespoon of common salt and one tablespoon of ammonium chloride and mix them thoroughly.
- Examine the mixture to determine if it is heterogeneous (composed of visibly different substances). Record the reasons for your conclusion.
- Transfer the mixture into a china dish.
- Take a glass funnel large enough to cover the dish and plug the mouth of the funnel with cotton.
- Invert the funnel over the dish as shown in figure 9.
- Set up the dish with the inverted funnel on the stand of a stove.
- Apply heat to the mixture and observe the walls of the funnel.
- Initially, you will notice vapors of ammonium chloride rising and then solidifying on the walls of the funnel.
- Try this process with mixtures that contain camphor or naphthalene.
Experiment Observations:
- The mixture of common salt and ammonium chloride is homogeneous or heterogeneous.
- Upon heating, the ammonium chloride vaporizes and then solidifies on the walls of the inverted funnel.
Precautions:
- Handle the stove and heating apparatus carefully to avoid accidents.
- Perform the experiment in a well-ventilated area to prevent the buildup of harmful vapors.
- Use appropriate safety measures, such as wearing gloves and goggles, while handling chemicals and heating equipment.
Lesson Learnt from Experiment:
Through this experiment, students will learn that some mixtures can be separated by sublimation. In this case, ammonium chloride, being a substance that sublimes, changes from a solid directly into vapor upon heating and then solidifies again on cooler surfaces. This phenomenon can be utilized to separate ammonium chloride from other substances in the mixture.
