Observing and deciphering Chemical Changes
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.
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.
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
Observations of Reaction
NaHCO3 and HCI - C02
Once HCl had been added, the mixture remained clear and bubbles formed.
HCI and BTB
When the BTB was added, the clear HCl immediately turned an orangey-yellow. C1
NH4OH and BTB
When the NH4OH was added, it turned pink in the well plate. As the BTB was added, the mixture remained blue. *C1
NH4OH and BTB (redone)
The NH4OH was clear initially and once the BTB was added, the mixture remained blue. D1
HCI and blue dye
The HCl went from clear to green once the blue dye was added. A2
Blue dye and NaOCI
When 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. F
KI and Pb(NO3)2
The KI was clear and once the Pb(NO3)2 was added, the mixture suddenly turned into a thick yellow precipitate. G
NaOH and phenolphthalein
As the phenolphthalein was added, the clear NaOH turned a bright pink magenta color. H
HCI and phenolphthalein
The HCl was clear and when the phenolphthalein was added, the mixture remained...
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