Hard & soft water

The video explains the concept of water hardness, distinguishing between soft and hard water. Hardness is caused by calcium ions from soluble salts in rocks. Rainwater is soft because it lacks these salts. Temporary hardness, caused by calcium carbonate, can be removed by boiling, while permanent hardness, from calcium sulfate, cannot. Soap forms scum in hard water due to calcium ions, but detergents do not have this issue. The video concludes with a summary of these concepts.

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