A Reducing Sugar Practice - IPSE FPMIPA UPI Report of Science Lab 2
SCIENCE LAB 2
A Reducing Sugar
Introduction
A reducing
sugar is any sugar that either has an aldehyde group or is capable of forming one in solution through esoterism.
The aldehyde functional group allows the sugar to act as a reducing agent,
for example in the Benedict test,
important in the browning of many foods. Generally, Any
carbohydrate which is capable of being oxidized and causes the reduction of
other substances without having to be hydrolyzed first is known as reducing
sugar. Benedict Reagent's is used to test for the presence of a
reducing sugar. The reducing sugar reduces copper (II) ions in these test solutions to copper(I), which then forms a brick red copper(1)oxide precipitate. And all carbohydrates
(except sucrose) respond positively to Benedict's Reagent but the test has a faster rate when it comes to monosaccharides.
Methods
-
Materials
and equipments
1.
Glucose
solution (1%)
2.
Benedict’s
reagent (qualitative)
3.
Boiling
tube (2)
4.
Beaker
(250 cm3)
5.
Pipette
(2)
6.
Hot
water bath (80Oc – 100oC)
7.
Test-tube
rack
8. Labels
-
Procedure
1.
Materials
and equipments were prepared.
2.
Boiling
tube A was given a label ‘glucose solution’ and boiling tube B was ‘water’ as a
label.
3.
2
cm3 of glucose solution was poured into boiling tube A.
4.
2
cm3 of water was poured into boiling tube B.
5.
2
cm3 of benedicts reagent were added into each boiling tube.
6.
Each
tube was swirled.
7.
Both
tubes were placed in the hot water bath and heated for 5 minutes.
8.
Both
tubes were removed carefully from the hot water bath and placed it to the
test-tube rack.
9.
The
result was recorded.
Result
|
Sample |
Initial
color |
Final
color |
|
A-glucose |
Glucose
is colorless but when it was added
by benedict’s reagent, the color turned into blue. |
The
color of the glucose when it was added by benedict and heated, it was changed
from blue into orange but
continously turned into bricked-red. |
|
B-water |
Water
is colorless, it was changed
become blue after it was
poured by benedict. |
The
color of water after it was added benedict and heated is still blue. |
Discussion
Reducing sugar reduces
the benedict reagent or the blue
Cu2+(copper II ions) in these test solutions to Cu+ (copper I ions). These are
precipitated in form of red or bricked-red Cu2O (copper oxide) and insoluble in water. This bricked-red color indicates that the large
amounts of reducing sugars present and it appears in the experiment.
References
http://igbiologyy.blogspot.co.id/2012/12/31-benedicts-test-for-reducing-sugars.html
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