Explore water's hardness, the difference between temporary and permanent hardness, and methods to soften water.
Hard water contains dissolved calcium and magnesium salts, which prevent soap from lathering easily. Soft water lathers easily with soap.
Why doesn't soap lather well in hard water?
The calcium and magnesium ions react with soap to form an insoluble scum instead of lather
What causes water to be 'hard'?
Dissolved calcium and magnesium salts
Temporary hardness (caused by bicarbonates) can be removed by boiling. Permanent hardness (caused by sulfates/chlorides) requires other methods like adding washing soda.
How can temporary hardness of water be removed at home?
By boiling the water, which decomposes the bicarbonates and precipitates them out
Why doesn't boiling remove permanent hardness?
Because permanent hardness is caused by sulfates and chlorides, which don't decompose with heat like bicarbonates do
1. What causes water to be hard?
2. How can temporary hardness be removed?
3. What substances cause permanent hardness?
4. Name one method to remove permanent hardness.
5. Why is hard water a problem for soap use?