Water Hardness

Key Concepts

Removing Pollution And Hardness From Water By Precipitation Methods

1. The toxicity of heavy metal ions depends on the concentrations. The greater the concentrations are, the greater the toxicity is.

2. The precipitation process can be used to lower the concentrations of the heavy metal ions.

3. Acid rain or the acids act as humus to make the soil contain humus. It contacts with limestone (CaCO3), so the acids will react with CaCO3 and then dissolve it. Moreover, atmospheric carbon dioxide dissolves in water and produces “carbonic acid”.

4. Ca2+/ Mg2+ cause water to taste bitter. There are white deposits of CaCO3/ MgCO3 leaving by the dissolved material in hard water. They will stay in pipes and kettles. The hardness affects and intervenes the cleaning by using soaps.

5. We can use washing soda to soften water. If the water is called permanently hard, it contains Ca2+/ Mg2+ and does not contain HCO3. If the water is called temporarily hard, it contains all Ca2+/ Mg2+ and HCO3


Tutorial Videos-1 :    3-9.mp4 ,     

Tutorial Videos-2 :



Worksheet:   3-9Chem12-Answer Key 1.docx ,     3-9Chem12-Worksheet1.docx ,     ws1_Chem12-Worksheet-2.docx ,     ws1key_Chem12-Answer-Key-2.docx ,     


Hard Water Reflection Posts

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