Observation of chemical change LabPaq

8 August 2016

Certain Chemicals like Bromthymol blue and Phenolphthalein can be added to other chemicals to determine acidity or basicity. Other reactions can be observed as well when different chemicals are added to each other. Procedure This experiment involved placing drops of specified chemicals into a well on a 96­well plate. Each well number was recorded along with question number and name of chemicals involved. Two drops of a chemical were placed in a well along with two drops of another chemical. Chemical reactions and color changes were recorded in Data Table 1. Observations

During the experiments a few problems were encountered. One of the chemicals provided differed slightly from chemical description in the lab manual. The lab manual called for the chemical NH3 which is Ammonia. The chemical provided was an Aqueous Ammonia solution of NH4OH. When holding up the solution of AgNO3 and NH4OH to a light source for 5 minutes it was observed that no reactions took place despite the information contained in the lab manual. Also while testing the household chemical Brite, It was observed that the Bromthymol Blue changed to a green color that was not observed in any other test involving BTB.

Observation of chemical change LabPaq Essay Example

Questions A. Suppose a household product label says it contains sodium hydrogen carbonate (sodium bicarbonate). How would you test this material for the presence of sodium bicarbonate? To test for the presence of sodium bicarbonate you could collect a sample of the household product and add HCl to it and see if you observe any CO2 bubbles. B. You know what color phenolphthalein and bromothymol blue turn when testing an acid or a base. Use the empty pipet in the Auxiliary Supplies Bag to test several (at least 3) household items including household cleaning products with bromothymol blue.

Rinse the pipet well before using it on the next household chemical. When finished with this experiment rinse the pipet well and return it to the Auxiliary Bag for use in future experiments. Name the items tested and record their results. What do these results mean? Refer to the last 3 rows of Data Table 1 for results and observations of the household chemicals. C. You found a sample of a solution that has a faint odor resembling vinegar. You are verifying that it is indeed vinegar and you add a few drops of phenolphthalein. The sample turns pink. What assumption can you make about this sample?

You can assume that the solution is not vinegar because vinegar is an acid and phenolphthalein only turns a basic solutions pink. D. You decided to investigate if the new wave of Vitamin Water is pH neutral: neither too acidic nor too basic. Using BTB (bromothymol blue), you select five flavors of Vitamin Water to test. Three of the flavor­samples turn a murky green, indicating the likelihood of acid/base balance. Of the two remaining, one turns slightly yellow, while one remains b lue. What can you assume about the acid/base content of these particular flavors of Vitamin Water?

You can assume that the vitamin water that stayed blue has a more basic content while the vitamin water that turned slightly yellow has a more acidic content then the three vitamin waters that turned murky green. E. You have read that a new brand of hair tonic is supposed to contain lead (an ingredient in Grecian Formula). Devise a simple test to confirm the presence or absence of lead in that hair tonic. A simple experiment to test for the presence or absence of lead would involve adding potassium iodide to a sample of the hair tonic.

If you observe a yellow and chalky looking precipitate when you add the Kl there is most likely lead in the hair tonic. Data Table ­ 1 Well # / Question Chemicals Reaction # A­1 A NaHCO3 and HCl ­ CO2 Small amount of CO2 bubbles formed but no color change # A­3 B HCl and BTB Turned Light orange orange color # A­5 C NH4OH and BTB Blue color showing that acids will be orange and bases will be blue when using BTB # A­7 D HCl and Blue Dye Color changed to green # A­9 E Blue Dye and NaOCl No reaction, The color stayed blue until HCl was added then changed to blue green color

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