Observe crystallisation of Sugar in Changes around Us – Class 7 Science Experiment
Chapter Name: Changes around Us
Activity Name: Observe crystallisation of Sugar in Changes around Us
Activity Description:
This experiment aims to observe the crystallization of sugar from a saturated sugar solution. By continuously adding sugar to water and heating the solution, we reach a point of saturation where no more sugar can dissolve.
After filtering the solution and letting it cool, we will observe the formation of sugar crystals.
Required Items:
- Big size test tube
- Water
- Sugar
- Heat source (e.g., Bunsen burner or stove)
- Stirring rod
- Filter paper or sieve
- Timer or clock
Step by Step Procedure:
- Take a big size test tube and fill it halfway with water.
- Add some sugar to the water and stir until the sugar is dissolved.
- Continue adding sugar to the water while stirring until saturation is achieved. This is the point where no more sugar can dissolve, and there might be some undissolved sugar at the bottom of the test tube.
- Heat the sugar solution gently while stirring continuously. This step is to ensure that the maximum amount of sugar is dissolved.
- While the solution is still hot, add some more sugar to it and stir continuously until no more sugar can dissolve. There should be no visible sugar left at the bottom of the test tube.
- Allow the sugar solution to cool down for half an hour.
- After the cooling period, filter the solution using filter paper or a sieve to remove any impurities or remaining undissolved sugar.
Experiment Observations:
At the end of the experiment, you will notice that the sugar solution has become supersaturated. This means that it contains more dissolved sugar than it can normally hold at the current temperature. As the solution cools down, the excess sugar will start to come out of the solution and crystallize. You will observe the formation of sugar crystals in the test tube.
Precautions:
- Be careful while handling hot objects and heating equipment.
- Stir the solution gently to avoid splashing.
- Use a proper filtration setup to filter the solution effectively.
Lesson Learnt from Experiment:
This experiment demonstrates the process of crystallization, where a supersaturated solution releases the excess solute and forms crystals. It also highlights how heating the solution can increase its capacity to dissolve more solute, which results in a supersaturated state upon cooling.
