Water testing Lab report

Katrina Cymerman

Chemistry

Dr. Forman

06/21/11

Lab Report for the Water Testing Lab

Abstract- For the Water testing lab we needed to test each substance for the presence of Calcium Ion, Iron Ion, Chloride Ion, and Sulfate Ion. We tested for each substance by placing at least three drops of different solute for each test. For the Calcium Ion we needed to use sodium carbonate in order to detect whether there were traces of the ion in the water. To test for Iron we used potassium thiocyanate and only had results in the control and reference. The reaction caused an almost blood red color and solids to form. For the Chloride ion test wee used silver nitrate, which was a dangerous substance and needed hand protection, and we found reactions in ocean water, control, and reference. Then for the Sulfate ion we used barium chloride in order to get a reaction in the distilled water, ocean water, reference, control, and tap water. In each test we found the impurities in water; therefore, the tests were successful.

Procedure- Obtain materials: ocean water, control, bottled water, silver nitrate, Barium chloride solution, calcium chloride solution, ferric initrate solution, ferris solfate solution, potassium thyocyanate solution, well plate, stir rod, tape (to label). For the Calcium Ion (Ca²⁺ ) test we added 20 drops of distilled water in the first dip, labeled it, and then put the put three drops of sodium carbonate directly afterwards. After the distilled water observations we place 20 drops of the control liquid in the second dip and labeled it control, and then we dropped 3 drops of the sodium carbonate into that. After observing and writing down the reaction to the control we dropped 20 drops of the calcium chloride (Ca²⁺ ) reference solution into the third dip and dropped three drops of the sodium carbonate. Then we put 20 drops of ocean water into the fourth dip and put 3 drops of sodium carbonate into the solution and observed and after we did the same process to the tap water. After cleaning out the well plate my group started working on the iron test. For the Iron (III) ion (FE ³⁺) water test we used the same materials and repeated the same procedures. In the first dip we placed 21 drops of distilled water (one accidentally drop), in the second dip we placed 20 drops of the control, in the third dip we placed 20 drops of the ocean water, in the fourth dip we placed 20 drop of the Iron reference, which was ferric nitrate and we got confused on weather to use feriss solfate or the ferric nitrate and put 20 drops of the feriss solfate into a dip in the second column; in the second dip on the second column we put 20 drops of tap water. After placing all the solutions with the correct labeling and with the correct amount we put 3 drops of potassium thiocyanate into each dip in the well plate and observed and documented the results. After we had finished the Iron testing we cleaned out the well plate again and began to work on the next test. The Chloride ion test was the next test in the instructions. We placed 20 drops of distilled water into the first dip and put 3 drops of silver nitrate into the solution then we placed 20 drops of the control into the second dip and added 3 drops of the silver nitrate; we placed then placed ocean water into the third dip and put 3 drops of silver nitrate, and we dropped 20 drops of the reference which was calcium chloride into the fourth dip and put 3 drops of the silver nitrate into that solution and observed and documented the reaction. Finally we placed 20 drops of tap water into the second dip on the second column and dropped 5 (accidentally added 2 more) drops of silver nitrate into the solution and observed and documented any occurrence. Finally, after re-rinsing the well plate, we began our last test, which was Sulfate Ion (SO^2- ). We placed 20 drops of the distilled water into the first dip, then we put 20 drops of the control into the second dip, 20 drops of ocean water were added to the third dip, 20 drops of the reference, which was feriss solfate were added to the fourth dip, and finally 20 drops of tap water were added to the second dip on the second column. After adding 3 drops of the Barium chloride to each solution we recorded the results and clean our station and supplies. Also for most of the time we wore gloves to protect our hands again the chemicals.

Results- For the first test, the Calcium Ion (Ca²⁺ ) test, our results were interesting. In the distilled water nothing seemed to happen and no precipitate was present nor was there a color change, yet in the control we observed that a precipitate was formed and it looked cloudy. In the ocean water very small precipitates formed and the water looked cloudy and in the reference precipitate was formed and made the appearance cloudy as well. Finally in the tap water after adding the sodium carbonate only very tiny precipitate formed. The reason the reactions occurred was because there was traces of Calcium Ions in some of the substances. For the Iron test when potassium thiocyanate was added to distilled water nothing happened; however, when added to the control and reference, the solutions changed to deep reds and precipitate was formed in both. When added to the ocean water nothing happened and when added to the tap water nothing happened. Each reaction happened because there was some type of trace or presence of Iron ions in the reacting substances. For the Chloride Ion test the distilled water had no reaction to the silver nitrate, the control had a big reaction with a color change to white and precipitate formation, the ocean water had big precipitates and pure white color, the reference changed to a pure white color with large precipitates as well, and the tap water, after an accidental addition of two drops over three, nothing happened. These reactions happened because there was some trace of chloride ions inside the solutions that had reactions.  In the Sulfate Ion  (SO^2- ) test the results after addition of the barium chloride were: for the distilled water a little bit of white appeared and made the substance cloudy, in the control there was precipitate and it was very cloudy white color, in the ocean water there was precipitate and cloudiness of the substance, in the reference the color was white and precipitates were formed, and in the tap water there was a small reaction with very small precipitates. Each reaction occurred because there was a trace or presence of Sulfate Ions in the substances that had a reaction. The results were all different and some were unexpected.

Questions-

1. A reference solution and blank were used in order to see the difference between a reaction and a non-reaction.
2. Some possible problems associated with the use of qualitative tests could be that they only tell whether there is a presence or an absence of a substance not the amount, which can cause issues because some elements that are in water are needed in very small amounts; however, the elements could become to large of a presence in the water and cause more damage that help.
3. The tests cannot absolutely confirm the absence of an ion because there is no way to exact test for an absence of a substance; scientists just need to use deductive reasoning to figure out what ions are in the water.
4. The observations would have changed if my group hadn’t cleaned out our tools thoroughly because we could have contaminated our samples and observed false positives instead of the actual results.

Data tables