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Testing Hardness of water

Shubhangi Mishra
Critical thinking, Problem Solving
Remember, Understand, Application

Testing Hardness of water
1.Soap solution is used to measure the hardness of rain water, temporarily hard water and sea water.2. The effect of boiling the hard water samples is investigated.
The students understand how water when reacts with calcium and magnesium and other compounds and and minerals results into formation of hard and soft water.
Eye protection

Measuring cylinders (10 cm3), 5 (one for each of A to E below)

Each group of students will need:

Conical flask (100 cm3)

Bung, to fit the conical flask

Burette and burette stand

Small funnel


For Further details:
1. How could you use a flame test to distinguish between hard and soft water?
2. After a period of time, your ion-exchange water softener no longer removes hard-water ions. How can you "refresh" your water softener, using a material obtained from the grocery store?
3. The deionized water in the Chemistry Department is produced by ion exchange that uses H+ ions, rather than Na+ ions, to replace the cations found in the water. Briefly, explain why the pH of deionized water is typically found to be around 6.
4. Explain why solutions of Ca2+ and Mg2+ in the presence of carbonate leave deposits (see Equation 1), but Na+ does not.
5. Write the net ionic equation for the removal of calcium ions by precipitation with carbonate in the lime-soda process. (See the introduction to Experiment 2 for a discussion of net ionic equations.)
6. Could sodium ions be removed in the same way as magnesium ions in the lime-soda process (i.e., by addition of hydroxide) for individuals concerned about their sodium intake? Briefly, explain your reasoning.
Accurate, Clearly explained, Complete, Knowledgeable, Methodical, Precise, Well crafted/ articulated, Informative

The more application based question you ask children they understand the concept better.
The brainstorming questions can be used by class 9, 10 and 11th students also.

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