The Liquid State
Chapter Name : States Of Matter |
Sub Topic Code : 102_11_05_11_02 |
Topic Name : The Liquid State |
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Sub Topic Name : Surface Tension |
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Introduction
Surface tension is the attractive forces between molecules on the surface of fluids. It the reasons why liquids like mercury and water form drops instead of spreading along the surface.
Pre-Requisites:
Intermolecular forces
Activity:
Use of detergents to wash clothes.
Real Life Question:
Why are detergents used to wash clothes?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Surface tension | • The molecules of the liquid on the surface have no molecules above them, so they have stronger attractive forces on the molecules on the sides and below. • This strong attractive force at the surface is called surface tension. . |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Paperclip, glass of water | Gently put the paper clip over the water surface and you would observe the clip floating. If you disturb the surface tension by agitating the water, the clip would eventually drown. |
Real life uses :
Washing clothes with detergents.
Places to visit :
Laundry, pond of water, garden
Practical examples around us
| Examples | Explainations |
|---|---|
| Use of detergents | Soaps and detergents are used to decrease the surface tension of water so that the clothes can be soaked well. |
What you learn in Theory:
Surface tension takes place due to the attraction of adjacent molecules in a fluid.
What you learn in Practice:
Surface tension helps to lighter objects to float on fluids.