Lab Report: Water Testing

Abstract: Its important to know what's in your water. For example, in Riverwood, students and scientists found dead fish in the town's water supply. The scientists needed to take samples and test the water to see if contaminants were present. This same theory was applied in our water testing investigation. During the water testing lab, our class was testing an unknown sample of water to see which ions were present.

Procedure:

Calcium Ion Test

1) Drop 20 drops of solution into a well; repeat this step for each sample (reference, blank, tap water, natural water)
2) In the well, place 3 drops of sodium carbonate solution; repeat this step for each sample
3) Discard the solutions in the well plate
Iron III Test 
1)  Drop 20 drops of solution into a well; repeat this step for each sample (reference, blank, tap water, natural water)
2) In the well, place 1-2 drops of potassium thiocyanate reagent; repeat this step for each sample
3) Discard the solutions in the well plate

Chloride Ion test 

1)  Drop 20 drops of solution into a well; repeat this step for each sample (refere 
nce, blank, tap water, natural water)
2) In the well, place 3 drops of silver nitrate reagent; repeat this step for each sample
3) Discard the solutions in the well plate

Sulfate Ion Test

1)  Drop 20 drops of solution into a well; repeat this step for each sample (reference, blank, tap water, natural water)
2) In the well, place 3 drops of barium chloride reagent; repeat this step for each sample
3) Discard the solutions in the well plate

Results:
1) In the calcium ion test, both the tap water and natural water tested negative for calcium because the mixtures had no color and were not cloudy.
2) In the iron III ion test, both the tap water and natural water tested negative for calcium because the mixtures had no color and were not cloudy.
3) In the chlorine ion test, both the natural water and tap water tested positive in the confirming tests and had a cloudy appearance
4) In the sulfate ion test, the tap water tested negative because there was no change in appearance, but the natural water was positive because it had a cloudy precipitate.

Questions: 
1) Both blank and reference solutions were used during the procedure because this way we could compare the unknown solution to the others.
2) A possible problem with the qualitative test is if there are contaminants left, then they could test as false positives.
3) These tests cannot absolutely confirm the absence of an ion because the ion can be present in low concentration.
4) My observations might have changed because substances being mixed can lead to a false reading.