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Potassium Iodide Lab

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Introduction

Lindsay Zackeroff Mr. Mardulier/4 Chemistry Honors 2/27/08 I. Title: Finding the Formula for Lead Nitrate II. Purpose: This experiment was to test the different concentration levels of specified alkali metals to determine the greatest mass of lead nitrate. III. Background Information: Potassium Iodide Potassium Iodide is a crystallized, white salt but known to turn a bright yellow when exposed to prolonged moisture such as mixing with water. It is a simple iodine salt. In its natural state it is mostly colorless and odorless. If tasted, it would be like saline and extremely bitter and is has a relatively low level of hazard. Its main use is in photography but also used in table salt to "iodize" food and can be used in expectorants for lung congestion. It can also be used to protect the thyroid from radioactive iodine Potassium iodide IUPAC name Potassium iodide Other names Kalium iodide, knollide, potide Identifiers CAS number [7681-11-0] RTECS number TT2975000 Properties Molecular formula KI Molar mass 166.00 g/mol Lead Nitrate Lead Nitrate is a hazardous colorless crystal or white powder. It has a long history of uses. Until 1974, when the dangers of lead were realized, it was in a variety of products. Lead(II) nitrate IUPAC name Lead(II) nitrate Other names Lead nitrate Plumbous nitrate Lead dinitrate Plumb dulcis Identifiers CAS number [10099-74-8] RTECS number OG2100000 Properties Molecular formula Pb(NO3)2 ...read more.

Middle

e) cautions: One must ensure to Read the meniscus at the proper point Use a plastic graduated cylinder for elimination of meniscus Measure by getting down at eye level Carefully take proper measurements Use two filter papers for double filtration Zero the scale after first weighing the filter paper Use an electronic scale for accuracy Product enhancements to minimize error Digital scale Pipette's measurements to allow a few drops of solution to be retained Plastic graduated cylinders for no confusion figure 1: rinsing setup figure 2: Pipette dispensing of liquids figure 3: filtering apparatus VII. Analysis The lab performed was found to be an effective way of discerning the formulation of lead nitrate and potassium iodide's precipitate and use the chemical formula to understand the reaction. The formula is as follows: KI + Pb(NO3)2 --> PbI + K(NO3)2. Potassium Iodide and Lead Nitrate yield Lead Iodide and Potassium Nitrate. The reaction taking place is known to be a double replacement. The two compounds split and then combine with the counterparts. The PbI remains in the solution and the K(NO3)2 forms the precipitate. The purpose of the experiment was to find which combination of concentrations would consequently have the greatest impact on the mass of the Lead Iodide. It was found that when the concentrations of each are 5:5, the filtration leaves a substantial amount of the liquid and the yellow precipitate known as lead iodide is at the peak of the masses. ...read more.

Conclusion

Another space for error is the filter papers. Some of them were larger than the others. This can distort the results. The same filter paper should be used for all of those participating in the tests. The papers also varied in thickness. Others used only one paper, allowing too much precipitate through, and others used more than two. This allows the paper to absorb too much liquid instead of filtering it all the way through. An additional problem is evaporation. Leaving the filtration apparatus uncovered could allow gradual evaporation. Quite oppositely, the humidity in the room could also cause tampering with the solution. With the weather changes, the temperature of the lab was not held at a constant. One day it was heated the next was at a very cool temperature. This could easily have an effect on the experiment. All these reasons could have a great deal in the variety of results. The experiment would need to be performed again to accurately portray the data. Human error would need to be nonexistent VII. Conclusion As previously stated, the results of the experiment were not all in agreement. The different classes obtained various results. This can be due to human error. After realizing the effects on the reaction taking place, it was also discernable how concentration can easily affect the combination. However valuable knowledge on the formation of lead iodide was gained from this lab and the purpose was successfully completed. ...read more.

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