Hard and Soft Water – What Is Your Taste? (2009-10)

Name ______Name ______

Class ______Date ______

Background Information

1.  What is meant by “hard water”? (What minerals are found in hard water?)

2.  What causes water to be hard?

3.  What effects, if any, does hard water have on a person’s health?

4.  How can hard water be softened? Explain how the process of ion exchange works.

5.  Many people have water softeners in their homes. Why is it important and worth the cost to soften water in your home?

6.  What is the function of the resin bed in a water softener? (You must be specific – what exactly happens in the resin bed – include the chemistry?)

7.  Why is salt periodically flushed through the resin bed? (You must be specific – what exactly happens when the resin bed is flushed with salt – include the chemistry)

8.  Are there any harmful effects of using a water softener?

9.  Do you have a water softener in your home? Why or why not?

A. Hard Water: What is Hard Water

http://coffeetea.about.com/cs/water/a/hardwater.htm

B. Chemistry of Hard and Soft Water

http://chemistry.about.com/cs/howthingswork/a/aa082403a.htm

C. Neb Guide: Drinking Water: Hard Water

http://elkhorn.unl.edu/epublic/pages/publicationD.jsp?publicationId=175

D. Water Softener: Frequently Asked Questions

http://www.lenntech.com/water-softener-FAQ.htm#1

· Table I. Classification of water hardness (hardness as calcium carbonate).
Classification / mg/l or ppm / grains/gal
Soft / 0 - 17.1 / 0 - 1
Slightly hard / 17.1 - 60 / 1 - 3.5
Moderately hard / 60 - 120 / 3.5 - 7.0
Hard / 120 - 180 / 7.0 - 10.5
Very Hard / 180 & over / 10.5 & over

(ppm CaCO3) / 17.1 = hardness in grains per gallon

Lab Procedure:

1.  Test the hardness of the stream water and the faucet water in mg per liter (same as ppm) . Record in mg/ of calcium carbonate and in grains per gallon

2.  Clamp the bottom of the water “softener”. Fill with faucet water. Allow to soak for about a minute. Release into small beaker. Run through softener one more time.

3.  Retest the treated faucet water. Record results.

Analysis:

1.  Which had the hardest water BEFORE running through the resins, the creek water or the faucet water?

1.  What effect did the resin bed have on the water? SPECIFY the differences in ppm before and after treatments

2.  EXPLAIN what happened, on a chemical level, in the resin bed?

3.  By what percent did the resin bed reduce the level of hardness? Show calculations

Water / CaCO3 ppm - before treatment / Grains/gallon
Before treatment / CaCO3 after treatment ppm / Grains/gallon after treatment
Creek
faucet