Water Softening Notes

WATER SOFTENING NOTES

Pre – lab discussion questions:

1.  What types of ions are present naturally in freshwater supplies?

o  Ca+2, Mg+2, Fe+3

2.  How did they get there?

o  Rainwater passes through soil, and minerals are dissolved (do you think these are polar or non-polar minerals?)

3.  Since one of the major minerals that provide hard water ions is CaCO3 (limestone) – do you think that this area of the country would be subject to hard water? (this assumes knowledge about the geology of Ohio)

4.  What makes them good / bad?

o  They ARE NOT bad for you – in fact, aren’t they essential minerals?

o  However – Hard water ions cause undesirable effects:

§  Soap will not lather well – so you use much more of it

§  Iron can cause unsightly rust stains on fixtures

§  Magnesium and Calcium form insoluble deposits, scum

§  Can also cause dry skin, dull hair (due to deposits)

5.  How do we get rid of the bad ones?

o  Products that soften water, like Calgon or…. Most of us use water softeners that incorporate the concept of ion exchange

6.  How would we determine the effectiveness of our attempt to get rid of the bad ions?

o  Sudsing ability with soap (the more suds – the SOFTER the water)

o  Precipitation of the ions with sodium carbonate (if the ions are still present they will form a cloudy precipitate when tested)

Post lab discussion questions:

1.  So… what is the best method of softening water from the methods we tried?

2.  How did you determine the effectiveness?

3.  How do water softeners work?

4.  If we use NaCl to “recharge” the ion exchange resin in water softeners – are there any potential problems with the fact that the water no longer contains calcium, magnesium, or iron - but it DOES contain sodium?