THE ABILITY OF SALT, NAHCO3
AND VINEGAR FOR WASHING
BLEACHING AGENT IN BEAN SPROUT
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Members
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Advisor
 Dr. Usa Jeenjenkit
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Introduction
 Have you ever eaten bean sprout ?
I am sure you have ever eaten it.
Because it is in many Thai dishes
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 But do you know that there are foxy
merchant use bleaching agent in bean sprout.
Na2S2O4
Sodium Hydrosulfite
Sodium Dithionite
And this chemical substance is toxic.
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 It made us thought that can we wash bleaching
agent in bean sprout ?
 but what we will use.
 Then we thought what our moms always use to
wash vegetable . It is NaCl Vinegar and NaHCO3
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Can The solution of Nacl , Vinegar and
NaHCO3 wash bleaching agent in bean
sprout better than pure water ?
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Material & Methods
For the experiment, we prepared 3 solution of
Vinegar, NaHCO3 and salt with 3 different
concentration
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First ,we used vinegar 2% , 3% and 5% V/V by using
500 cm3 of volumetric flask
: added Acetic acid (CH3COOH) 10, 15 and 25 cm3
into each flask ,filled in water until the volume of
solution was 500 cm3, mixed them together
example of vinegar
solution
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Then we used NaHCO3 3%, 4% and 5% M/V by using
500 cm3 of volumetric flask
: added NaHCO3 15, 20 and 25 g
into each flask ,filled in water until the volume of
solution was 500 cm3, mixed them together
NaHCO3
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Next, we used salt 3%, 4% and 5% M/V by using 500
cm3 of volumetric flask
: added salt 15, 20 and 25 g
into each flask ,filled in water until the volume of
solution was 500 cm3, mixed them together
example of salt
(NaCl) solution
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For chemical detection we use KMnO4
solution to test quantity of bleaching agent in
bean sprouts : dissolve 2 flakes of KMnO4 in 1
liter of water (=0.0677g/l)
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put 30 g of bean sprout in the 10 beakers
of solution (including water).
Vinegar 2%
Vinegar 3%
Vinegar 5%
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NaHCO3 3%
NaHCO3 4%
NaHCO3 5%
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NaCl 3%
NaCl 4%
NaCl 5%
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water
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waiting for 20 minutes
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Added KMnO4 solution 10 cm3
into the test tube mixed well and waited for
5 minutes
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then put away the bean sprout and put 10 cm3
of solution from each beaker into the test
tube.
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Test the changing of the color by using
spectrophotometer.
Note : use 400 nm
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Result
 Vinegar ability for washing bleaching agent
in bean sprout charts
0.6
2%
0.5
3%
0.4
5%
0.3
Abs
without Bean sprout
0.2
with Bean sprout
0.1
0
KMnO4 + water
Vinegar
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Vinegar ability for washing
bleaching agent in bean
sprout
2% 3% 5% without Bean sprout
KMnO4 + water
Vinegar
with Bean sprout
0.501
0.095
0.019 0.08 0.021
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 NaCl ability for washing bleaching agent in
bean sprout charts
0.6
0.5
0.4
3%
Abs 0.3
4%
5%
0.2
without beansprout
with bean sprout
0.1
0
KMnO4 + Water
NaCl
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Salt ability for washing
bleaching agent in bean
sprout
with
without Bean Bean
3% 4% 5% sprout
sprout
KMnO4 + water
3%
4%
without
beansprout
5%
KMnO4 + Water
NaCl
Salt
0.501
0.205
0.196
with bean
sprout
0.501
0.095
0.095
0.308
0.205 0.196 0.095
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 NaHCO3 ability for washing bleaching agent
in bean sprout charts
0.6
0.5
0.4
Abs
0.3
3%
4%
5%
0.2
without bean sprout
with bean sprout
0.1
0
KMnO4 + Water
NaHCO3
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NaHCO3 ability for washing
bleaching agent in bean
sprout
without Bean with Bean
3% 4% 5% sprout
sprout
KMnO4 + water
NaHCO3
0.501
0.095
0.192 0.186 0.361
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Discussion
 From this experiment , We can see that
Na2S2O4 can dissolve the best in vinegar
solution because vinegar solution can
decompose Na2S2O4 .(Mayer ,1992 )
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 We can assume that the NaCl solution and
NaHCO3 solution dissolve Na2S2O4 worse than
vinegar solution because they have Na+ ion that
dissolve in water already and it disturb the
dissolving of Na2S2O4
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 For this result ,it’s oppose with Aubrey result
because he said that all of vinegar, NaHCO3
and salt are good to wash the vegetable and
decompose toxic .
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Future research

This project will help your health by
washing the bleaching agent from the bean
sprout .If you want to continue this project ,
you can use other chemical substances to
wash bleaching agent from bean sprout .
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Suggestion
 if we have more time, we should do the
experiment again for 2-3 times to make sure
that we have accurate result.
 Maybe we use more kinds of solution to make
us know what the best cleaner solution other
than we used.
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References
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Aubrey.(2011). Vegetable Washing Tips. Retrieved August 7,2011, from
http://www.ehow.com /info_8635506_home-cleaning-sprays-made- bleach.html.
Dvorak, G. (2005 ,February). Disinfection. Center for Food Security and Public Health.
Ames,
IA: Center for Food Security and Public Health, Iowa State University.
p. 12. Retrieved
August 7,2011, from http://www.cfsph.iastate.edu /BRM/
resources/Disinfectants/Disinfection101Feb2005.pdf.
KFDA.(2009). Find sodium hydrosulfite at GFS Chemicals. Retrieved August 16,2011,
from http://www.chemindustry.com/chemicals/0523798.html.
Weinrach, J. B.; Meyer, D. R.; Guy, J. T.; Michalski, P. E.; Carter, K. L.; Grubisha, D. S.;
Bennett, D. W. (1992). A structural study of sodium dithionite and its ephemeral
dihydrate. Retrieved August 16,2011, from http://en.wiki
pedia.org/wiki/Sodium_dithionite.
Wiebold,D.(2007). Brief Introduction of Mung Bean. Retrieved August 8,2011, from
http://en.wikipedia.org/wiki/Mung bean.
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QUESTION
&
ANSWER
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