1. Lesson 9: Water Hardness
Unit 3: Solubility
Lesson 9: Water Hardness

2. What Is Water Hardness?
“Hardness” in water is the presence of Ca2+ and/or Mg2+ ions.
These ions come from mineral deposits in the ground, the most common being limestone (CaCO3).
Invermere

3. Why Does It Matter? Hard water tastes bitter (yuck).
Hard water inhibits the cleaning action of soaps (the ions react with soap to form scum).
Hard water leaves behind mineral deposits whenever water evaporates or is heated:
10 min

4. Brain Break – Spot 7 Differences!

5. Think-Pair-Share
Using only your solubility table and your brain, come up with at least three possible methods for removing hardness from water.
Which of your three methods is the best one? Why?
The most common method used is adding washing soda (Na2CO3), which causes CaCO3 and MgCO3 to precipitate out of the water.
15 min

6. Tableau!
In a group of three, create a tableau illustrating something you learned today.
You have five minutes to prepare, and then you will present your tableau to the class!
10 min