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Water
Chapter Name : Hydrogen
Sub Topic Code : 102_11_09_06_05
Topic Name : Water
Sub Topic Name : Hard And Soft Water
Introduction

• Water may be classified as hard water and soft water depending on the presence of salt. • Hard water contains calcium and magnesium salts in the form of hydrogencarbonate, chloride and sulphate. It thus forms a scum with soap. • Soft water is free from any soluble salts of calcium or magnesium and thus forms lather with soap.

Pre-Requisites:

Chemical properties of Water.

Activity:

When detergent is added to Epsom salt plus water, you see that very few bubbles are formed. This is because Epsom salt makes the water hard.

Real Life Question:

Why water is sometimes called as hard water?

Key Words / FlashCards
Key Words Definitions (pref. in our own words)
Hard water Water that contains calcium and magnesium salts in the form of hydrogencarbonate, chloride and sulphate is called as hard water.
Soft water Water free from soluble salts of calcium and magnesium is called soft water.
Learning aids / Gadgets
Gadgets How it can be used
Epsom salt Add epsom salt to a cup of distilled water.
Detergent Add detergent to this cup of epsom salt plus water.
Real life uses :

- It is important to know whether water is hard or not, as use of hard water can damage clothes, boilers and affect humans as well.

Places to visit :

Home.

Practical examples around us
Examples Explainations
Well Sometimes water from wells may be hard due to salt contamination.
What you learn in Theory:

Hardness of water.

What you learn in Practice:

Properties of hard and soft water.

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