Water Testing Lab Report

Water Testing Lab

June 25, 2013

Juliet, Rio, Nora

Dr. Forman

Purpose: To test for the presence of iron and calcium cations as well as chloride and sulfate anions.

Background/Significance: After testing various water samples in order to discover the presence of certain cations and anions, we have learned how to distinguish qualitative and quantitative properties. By doing this, we have also reached conclusions about the water samples that we would not have known before.

Abstract: In this experiment, we underwent various procedures in order to test for some cations and anions. From these processes, we have taken many valuable lessons. First, we learned that we must be careful and thorough if we hope to attain the correct results and complete our work efficiently and successfully. Second, we had to wash all of our materials not only to maintain a clean working environment, but also to achieve the qualitative data that we strived for. After attaining the results that we desired, we were able to discover what substances pollute our water.

Procedure:

Calcium Ion (Ca²⁺) Test

1. Place 20 drops of each sample (distilled water, reference, unknown, tap water, natural water) in a well plate
2. Add 3 drops of sodium carbonate to each sample and record your observations
3. Discard the contents and rinse the well plate

Iron (III) Ion (Fe³⁺) Test

1. Place 20 drops of each sample (distilled water, reference, unknown, tap water, natural water) in a well plate
   
2. Add 2 drops of potassium thiocyanate to each sample and record your observations
   
3. Discard the contents and rinse the well plate

Chloride Ion (CI^-) Test

1. Place 20 drops of each sample (distilled water, reference, unknown, tap water, natural water) in a well plate
2. Add 3 drops of silver nitrate to each sample and record your observations
   
3. Discard the contents and rinse the well plate

Sulfate Ion (SO₄^2-) Test

1. Place 20 drops of each sample (distilled water, reference, unknown, tap water, natural water) in a well plate
2. Add 3 drops of bacterium chloride to each sample and record your observations
   
3. Discard the contents and rinse the well plate

Results: From these experiments, our group obtained interesting data; some was correct, while others had errors along the way. After testing all of the samples for the presence of the calcium ion, iron ion, chloride ion, and sulfate ion, most of our results seemed reasonable; however, we did make one vital mistake. During the chloride ion test, when we were examining the distilled water, we received a reaction that turned out to be blue. After redoing the procedure and checking our work, we found a mistake and ended up with a clear sample that did not actually have a reaction. This was probably because we did not completely clean our materials and therefore, chemicals got mixed, causing a different appearance for the sample.

Calcium Ion (Ca²⁺) Test

Solutions	Observations	Results
Reference:	Cloudy with precipitate	Yes
Control:	No reaction, clear	No
Tap water:	No reaction, clear	No
Natural (ocean) water:	No reaction, clear	No
Distilled (blank) water:	No reaction, clear	No

Iron (III) Ion (Fe³⁺) Test

Solutions	Observations	Results
Reference:	Blackish, bloody, brownish red color	Yes
Control:	No reaction, clear	No
Tap water:	No reaction, clear	No
Natural (ocean) water:	No reaction, clear	No
Distilled (blank) water:	No reaction, clear	No

Chloride Ion (CI^-) Test

Solutions	Observations	Results
Reference:	White	Yes
Control:	White	Yes
Tap water:	Yellow	Yes
Natural (ocean) water:	Bluish, purple	Yes
Distilled (blank) water:	Clear (error – on our first try, it turned blue)	No

Sulfate Ion (SO₄^2-) Test

Solutions	Observations	Results
Reference:	No reaction, clear	No
Control:	Blue	Yes
Tap water:	Bluish, clear	Yes
Natural (ocean) water:	No reaction, clear	No
Distilled (blank) water:	Cloudy white	Yes

Class Data Results:

		H	He	Li	Be	B	C
Ca Test	Control	No	No	No	No	No	Yes
	Ocean	Yes	Yes	No	No	No	No
Fe Test	Control	Yes	Yes	No	No	No	No
	Ocean	No	No	No	No	No	No
Cl Test	Control	Yes	Yes	No	No	Yes	Yes
	Ocean	Yes	No	Yes	Yes	Yes	Yes
Sulfate Test	Control	Yes	Yes	Yes	Yes	Yes	Yes
	Ocean	Yes	Yes	Yes	Yes	Yes	Yes

Lab Questions #1-4 p. 45:

1. A reference solution and a blank were used in each test in order to compare the other samples with simpler ones.
2. The qualitative tests may easily be affected by not cleaning the well plate or pipet thoroughly. As a result, the correct reactions may not occur, leading to an error and a misconception of the final conclusion.
3. These tests cannot absolutely confirm the absence of an ion because many times, one cannot see the ions with the naked eye; therefore, the final result is nearly impossible to figure out when a substance is not completely visible.
4. Our observations might have changed if we had not cleaned our wells or stirring rods thoroughly after each test. Incorrect colors and reactions would be formed as a result of incorrect chemicals mixing.