Observing and Deciphering Chemical Changes

Topics: Chemical reaction, Chemical substance, Solubility Pages: 5 (1708 words) Published: September 27, 2014
Observing and deciphering Chemical Changes
Purpose
The purpose of this experiment is to observe reactions of chemicals that can be found in consumer products. Through observation, students should be able to interpret the chemical reactions and determine some characteristics, such as pH and solubility. Method 1.Pipets containing chemicals will be opened using scissors to snip the end and each pipet will be placed in a well of a 24-well plate. The scissors must be washed between each pipet. 2.A 96-well plate will be placed onto a white sheet of paper. 3.Each set of chemicals will be mixed by dropping two drops of the first chemical and then two drops of the second chemical into a well of the 96-well plate. 4.Each chemical reaction will be observed and the reactions will be recorded. 5.Three household cleaners will be diluted. 6.Two drops of each cleaner will be tested in the 96-well plate with 2 drops of bromothymol blue. Procedure and Data 1.Each pipet was opened by snipping the end off with scissors and then placed in the 24-well plate. The scissors were washed each pipet. 2.The 96-well plate was placed onto a white sheet of paper. 3.Each set of chemicals was mixed as follows and the observations of the reactions were recorded in Data Table 1.

A1) Two drops of NaHCO3 and two drops of HCl.
B1) Two drops of HCl and two drops of BTB.
C1) Two drops of NH4OH and one drop of BTB.
D1) Two drops of HCl and two drops of blue dye.
A2) Two drops of blue dye and two drops of NaOCl. One drop of HCl was then added. F) Two drops of KI and two drops of Pb(NO3)2. G) Two drops of NaOH and two drops of phenolphthalein.
H) Two drops of HCI and two drops of phenolphthalein.
B2) Two drops of NaOH and two drops of AgNO3.
C2) Two drops of AgNO3 and two drops of NH4OH. This mixture was then absorbed into the corner of a paper towel and held in direct sunlight for approximately 5 minutes. D2) Two drops of NH4OH and two drops of CuSO4.

4.Each of the three household cleaners, CLR, Windex, and Clorox Cleanup with bleach, was diluted by mixing five drops of the cleaner with approximately 25 mL of distilled water in a 100 mL beaker and then stirred with a stirring rod. 5.Two drops of each diluted cleaner was placed in individual wells of the 96-well plate and two drops of bromothymol blue was added to each. 6.The observations of each reaction were recorded in Data Table 1. 7.All remaining pipets containing chemicals were placed in a container in the hood.

Observations
When bromothymol blue reacts with a base, the mixture will not change color and will remain blue. When bromothymol blue reacts with an acid, the mixture will change from blue to yellow. When phenolphthalein reacts with a base, the mixture will change to a bright pink. When phenolphthalein reacts with an acid, the mixture will not change color and will remain clear. 

Data Table 1: Reactions Expected
Well#Chemicals Observations of Reaction
A1NaHCO3 and HCI - C02Once HCl had been added, the mixture remained clear and bubbles formed.

B1
HCI and BTBWhen the BTB was added, the clear HCl immediately turned an orangey-yellow. C1NH4OH and BTBWhen the NH4OH was added, it turned pink in the well plate. As the BTB was added, the mixture remained blue. *C1NH4OH and BTB (redone)The NH4OH was clear initially and once the BTB was added, the mixture remained blue. D1HCI and blue dyeThe HCl went from clear to green once the blue dye was added. A2Blue dye and NaOCIWhen the NaOCl was added to the blue dye, the mixture remained blue. As the HCl was added, the mixture immediately turn green and then became yellow. FKI and Pb(NO3)2The KI was clear and once the Pb(NO3)2 was added, the mixture suddenly turned into a thick yellow precipitate. GNaOH and phenolphthaleinAs the phenolphthalein was added, the clear NaOH turned a bright pink magenta color. HHCI and phenolphthaleinThe HCl was clear and when the phenolphthalein was added, the mixture remained...
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