Table of Contents
Activity 1.13: Sublimation Experiment with Camphor
Objective
To demonstrate the process of sublimation, where a solid directly converts into a gaseous state without passing through the liquid state.
Materials Needed
- A small amount of camphor (or naphthalene balls).
- A china dish.
- An inverted funnel.
- A cotton plug.
- A heat source (like a burner or candle).
Steps to Perform the Activity
- Crush a small amount of camphor and place it in the china dish.
- Cover the china dish with an inverted funnel.
- Plug the narrow opening of the funnel with cotton to prevent vapors from escaping.
- Heat the china dish gently with a heat source.
- Observe the changes in the camphor and the inner walls of the funnel.
Observations
- As the camphor is heated, it disappears without leaving any liquid residue.
- A white, crystalline deposit is formed on the cooler inner surface of the funnel.
Also Check – Chapter 1 -MATTER IN OUR SURROUNDINGS -Class 9 – Simplified notes
Concepts Behind the Activity
Sublimation:
Sublimation is the process by which certain solids directly change into their gaseous state when heated, skipping the liquid state. When the gaseous form is cooled, it directly converts back into a solid.
Why Sublimation Happens:
Some substances, like camphor, have weak intermolecular forces. When heated, their particles gain enough energy to overcome these forces and directly transition to the gaseous state.
Deposition:
The vaporized camphor particles lose energy upon touching the cooler surface of the funnel. They revert to a solid form, creating the crystalline deposits observed.
Learning Outcomes
Direct State Change:
Sublimation demonstrates that certain substances can bypass the liquid phase during state changes.
Application of Heat and Cooling:
Heat provides energy for the particles to transition from solid to gas, while cooling reverses the process.
Real-World Examples of Sublimation:
- Naphthalene balls in wardrobes sublimate over time, leaving no liquid behind.
- Dry ice (solid carbon dioxide) sublimates at room temperature, forming CO₂ gas directly.
Applications of States of Matter
- Purification of Substances: Sublimation is used to purify substances like iodine and camphor.
- Industrial Uses: Manufacturing dry ice for cooling and special effects.
- Everyday Life: Preventing pests by using naphthalene balls in clothes storage.
Intext and additional Question Answers on Activity Activity 1.13: Sublimation Experiment with Camphor
Question 1: What do you observe when camphor is heated in a china dish?
Camphor changes directly from a solid to a gas, forming white vapors without passing through the liquid state. It leaves no residue in the dish.
Question 2: What do you infer about sublimation from this activity?
Sublimation is the process where certain solids directly transition to a gaseous state without becoming liquid. This is possible due to the weak intermolecular forces in such solids.
Additional Question: Can sublimation occur in everyday items like naphthalene balls?
Yes, naphthalene balls used to repel insects sublimate over time, disappearing as their solid particles turn into gas.
Conclusion
This experiment shows that sublimation is a unique state change where solids directly become gases. It also illustrates how changes in temperature affect the energy and arrangement of particles in matter, making it a valuable concept in both science and everyday life.
