# Simple question.

1. Jan 19, 2005

### Erin_Sharpe

I have no idea where to begin for this one:

How do you dtermine if sulfate ions are present in tap water?

Thanks!

2. Jan 19, 2005

### chem_tr

Barium sulfate has a very low solubility in water, so concentrated sample of tap water may be tested with an excess of barium ions, say, barium nitrate. An additional test which can be done after precipitation occurs is that barium sulfate can be dissolved in hot concentrated sulfuric acid, but this is very dangerous. Precipitation might be enough for simple cases.

Sulfate ion is IR-active, so an infrared of the sample without considering water peaks might also be helpful; a peak system belonging to S=O vibration occurs at around 1000 cm-1.

3. Jan 20, 2005

### poolwin2001

$(CH_{3}COO)_{2}SO_{4}$is also insoluble.So if on addn of a little lead acetate,a white ppt is formed,it indicates presence of sulfate(sulphate in my place) ions .

Last edited: Jan 20, 2005
4. Jan 20, 2005

### poolwin2001

A cheecky answer will be by spectroscopy.

5. Jan 20, 2005

### chem_tr

Poolwin2001, are you sure the structure you wrote your first post is not PbSO4? Barium sulfate is less soluble than lead sulfate, but the latter is also okay by the way.

6. Jan 20, 2005

### poolwin2001

Oops.I guess you are right .It should be PbSO4.
Sorry for the error erin.
Thanks for correcting it.

7. Jan 21, 2005

### archie

SO4 ion detection

The simplest and probably cheapest way to determine the presence of sulphate ion in the water is by using Barium Chloride soln. ( BaCl2 is preferrable than Barium Nitrate because it's more water soluble). Dissolve about 5 to 10 gram of BaCl2.2H2O in 100 ml distilled water. To test the water, just add several drops of BaCl2 soln. If there's white precipitate and cloudy appearance then big chance that your water contains sulphate ion.
Other alternative is by using Lead (II) Nitrate or Silver Nitrate, but these two as not as reliable as BaCl2 because the solubility of the sulphate of lead and silver is greater than BaSO4.