winter 2018 chem 185 poster Sang Mi Suh

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Sang Mi Suh
Quantitative Analysis of Potassium Permanganate by Spectrophotometric
Methods
Results (continued)
Abstract
Possible factors affecting absorbance readings of
potassium permanganate solutions were investigated.
Parameters studied include water sources and the
potassium permanganate precipitate age. Various
concentration of potassium permanganate solutions
were prepared, with different water sources, and their
absorbance measured in timed intervals. By
eliminating potential factors of degradation through
experiments, it was concluded that the deionized
water was the biggest factor affecting the degradation
of potassium permanganate.
Methods
To eliminate potential factors of the degradation of
potassium permanganate, process of elimination was
employed. By changing one factor at a time, research was
conducted to understand which factor brought in the
most change. Potential factors include:
Discussion
As written above, four different waters were used to test the
degradation of KMnO4. When the source of water was
changed, there was a difference in the degradation.
After multiple experiments with different factors, it was
determined that the source of water was the biggest
factor in the degradation of potassium permanganate.
This was concluded after seeing that changing factors
such as UV light, instrument, and source of powder
showed no noticeable difference in the degradation of
potassium permanganate. Only when the water source
was changed we were able to see different
degradation results. Through graphs, it was found that
the reaction was first order. The graphs are shown
below. Determining that the reaction is first order, it
can be said that it is potassium permanganate reacting
with organics in the water that is causing the
degradation.
• Using Ultra-Pure water showed little to no change in the
absorbance levels of potassium permanganate.
• Using the water effected by the Thomas fire showed
escalated degradation as the water possibly contained
organics to react with the potassium permanganate.
• Using the new deionized water also showed degradation,
similar to the water effected by the Thomas fire.
• Using the old-deionized water also showed degradation,
although the change was less than the other two water
listed above.
A detailed graph posted below shows the difference in
degradation depending on the water source.
Absorbance vs Time (New Deionized
Water)
ln A vs Time (Old-Deionized Water)
20
40
60
80
100
120
140
160
180
1/A vs Time (New Deionized Water)
200
0,45
10
Absorbance vs Time (.00016 M)
0,4
9
-0,5
0,45
8
0,35
7
0,3
-1
0,4
1/A
Absorbance
6
ln A
UV Light
Instrument
Source of Potassium Permanganate Powder
Source of Water
• Ultra-Pure
• Deionized Water before school ‘fixed’ the tank
• New deionized water
• Water effected by Thomas Fire
0
5
-1,5
0,35
4
0,3
-2
Sam .00016
0,25
0,25
0,2
0,15
3
Absorbance
•
•
•
•
0
2
0,1
1
0,05
Diana .00016
Claire .00016
Линейная (Sam
.00016)
Линейная
(Diana .00016)
0,2
-2,5
0
Times (Hours)
0
20
40
60
80
100
120
140
160
180
Time (Hours)
200
0
0
20
40
60
80
100
120
140
Time (Hours)
0,15
Each experiment had a variable of the each factor, and
each factor was eliminated when it still showed
degradation of the potassium permanganate powder.
Conclusion
0,1
0,05
0
0
1
2
3
-0,05
4
5
6
7
Days
Absorbance vs Time (.000032 M)
Results
0,07
0,06
0,05
0,04
Sam .000032 M
Absorbance
Three out of the four factors – UV light, instrument, source of
Potassium Permanganate Powder – was eliminated when it was
discovered that the potassium permanganate was still
degrading at the same rate. However when the source of water
was tested, the degradation of potassium permanganate was
either halted or preserved.
Diana .000032 M
Claire .000032 M
0,03
Линейная (Sam .000032 M)
As using Ultra-Pure water showed the minimal change in
absorbance levels, it can be concluded that using Ultra-Pure
water or proper de-ionized water is ideal when conducting
this experiment. Using contaminated water can show
escalated degradation of potassium permanganate. As the
degradation of the potassium permanganate is substantial in
the first three days, it can be concluded that the experiment
should be conducted on the day the solution is made to get
more accurate results.
Линейная (Diana .000032 M)
Линейная (Claire .000032 M)
0,02
0,01
0
0
-0,01
1
2
3
4
Days
5
6
7
As shown in the graphs to the left, the old-deionized
water had the least effect on the degradation of
potassium permanganate
160
180
200
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