Introduction
The antioxidant vitamin C works to shield cells from the damaging effects of free radicals,
chemicals the body produces as it breaks down food, is exposed to tobacco smoke, or is
exposed to radiation from the sun, X-rays, or other sources. Heart disease, cancer, and other
illnesses could be caused by free radicals. Vitamin C is known to be a hydrophilic molecule,
composed of six carbons, similar to glucose. In the organisms, Vit C can be found in its reduced
form (ascorbic acid or ascorbate) or in its oxidized form called dehydroascorbic acid, which is a
product of two-electron oxidation of ascorbic acid. This vitamin is typically found in fruit and
vegetables such as, potatoes, tomatoes, spinach, and berries. It could also be found in the form
of capsules which help maintain immunity and are good to take if a person is on a diet due to
them being limited on the foods they can eat.
Vitamin C is essential for maintaining healthy cells, healthy skin, blood vessels, bones, and
cartilage, as well as for promoting wound healing. More impressive health benefits of vitamin C
include raising antioxidant levels, lowering blood pressure, preventing gout attacks, improving
iron absorption, boosting immunity, and lowering the risk of dementia and heart disease.
Control variables are the things that are kept the same in an experiment. The purpose of having
control variables is to enhance the validity by limiting other variables present. By having a
controlled variable, it allows for better understanding of the relationship between other
variables. When testing vitamin c, the controlled variables are temperature of the fruit (juice)
and the amount of solution used to test the vitamin c content. The independent variable is the
factor that is changed in the experiment, and in this case is the fruit juice. The dependent
variable is what is measured in the experiment and for this experiment is the vitamin c content.
This experiment was carried out to determine the level of vitamin c in different fruits, and the
aim at the end of the experiment was to find out which fruit had the highest amount of vitamin
c. As mentioned above vitamin c is important for protecting cells, so it is essential that people
know how to maintain the highest amounts of vitamin c. The experiment that was carried out
tells us which fruit had the most vitamin c and as a result could be recommended to people
who need to increase their vitamin c intake. The following results show the concentration in
different fruits:
Fruit sample Volume of vitamin c
Pineapple 1cm3/1.1cm3
Tomato 9.1cm3
Orange 1.8cm3
Kiwi 11.1cm3
Grapefruit 0.9cm3
, Method
Make up a 1% solution of vitamin C with 1 g of vitamin C in 100 cm 3; this is 10 mg
cm3.
b Make up a 1% solution of DCPIP.
Investigation
c Pipette 2 cm3 of vitamin C solution into a test tube.
d Using a graduated pipette or a burette, add 1% DCPIP drop by drop to the
vitamin C solution. Shake the tube gently after adding each drop. Add DCPIP
solution until the blue colour of the final drop does not disappear.
e Record the exact amount of DCPIP solution that was added.
f Repeat the procedure and calculate an average result.
g Repeat with the fruit juices to be tested. If more than 5 cm 3 of DCPIP are
completely decolourised, dilute the fruit juice and repeat the test. If the fruit juice
has a strong colour that will interfere with determining the end point, dilute the
juice before testing.
h Calculate the amount of vitamin C in the standard solution in mg cm 3. Calculate
how much vitamin C there is in each of the fruit juices in mg cm 3.
Changes in method
Used a syringe rather than a burette
1ml of DCPIP was added to a 100cm3 beaker
Fruit juice was added using a burette until the DCPIP changed colour
Calculated the amount of vitamin c and fruit juice used to change the colour of the
DCPIP
Used a burette and was filled with a 50cm3 fruit juice sample
Analysis of results
Grapefruit has the largest amount of vitamin c, since it required the least amount of
juice to change the colour of the DCPIP
Kiwi had the least vitamin c, as we can see from the table that it required the most
amount of fruit juice to change the colour of the DCPIP
The results would have been more accurate if we repeated the experiment for each fruit
twice
The antioxidant vitamin C works to shield cells from the damaging effects of free radicals,
chemicals the body produces as it breaks down food, is exposed to tobacco smoke, or is
exposed to radiation from the sun, X-rays, or other sources. Heart disease, cancer, and other
illnesses could be caused by free radicals. Vitamin C is known to be a hydrophilic molecule,
composed of six carbons, similar to glucose. In the organisms, Vit C can be found in its reduced
form (ascorbic acid or ascorbate) or in its oxidized form called dehydroascorbic acid, which is a
product of two-electron oxidation of ascorbic acid. This vitamin is typically found in fruit and
vegetables such as, potatoes, tomatoes, spinach, and berries. It could also be found in the form
of capsules which help maintain immunity and are good to take if a person is on a diet due to
them being limited on the foods they can eat.
Vitamin C is essential for maintaining healthy cells, healthy skin, blood vessels, bones, and
cartilage, as well as for promoting wound healing. More impressive health benefits of vitamin C
include raising antioxidant levels, lowering blood pressure, preventing gout attacks, improving
iron absorption, boosting immunity, and lowering the risk of dementia and heart disease.
Control variables are the things that are kept the same in an experiment. The purpose of having
control variables is to enhance the validity by limiting other variables present. By having a
controlled variable, it allows for better understanding of the relationship between other
variables. When testing vitamin c, the controlled variables are temperature of the fruit (juice)
and the amount of solution used to test the vitamin c content. The independent variable is the
factor that is changed in the experiment, and in this case is the fruit juice. The dependent
variable is what is measured in the experiment and for this experiment is the vitamin c content.
This experiment was carried out to determine the level of vitamin c in different fruits, and the
aim at the end of the experiment was to find out which fruit had the highest amount of vitamin
c. As mentioned above vitamin c is important for protecting cells, so it is essential that people
know how to maintain the highest amounts of vitamin c. The experiment that was carried out
tells us which fruit had the most vitamin c and as a result could be recommended to people
who need to increase their vitamin c intake. The following results show the concentration in
different fruits:
Fruit sample Volume of vitamin c
Pineapple 1cm3/1.1cm3
Tomato 9.1cm3
Orange 1.8cm3
Kiwi 11.1cm3
Grapefruit 0.9cm3
, Method
Make up a 1% solution of vitamin C with 1 g of vitamin C in 100 cm 3; this is 10 mg
cm3.
b Make up a 1% solution of DCPIP.
Investigation
c Pipette 2 cm3 of vitamin C solution into a test tube.
d Using a graduated pipette or a burette, add 1% DCPIP drop by drop to the
vitamin C solution. Shake the tube gently after adding each drop. Add DCPIP
solution until the blue colour of the final drop does not disappear.
e Record the exact amount of DCPIP solution that was added.
f Repeat the procedure and calculate an average result.
g Repeat with the fruit juices to be tested. If more than 5 cm 3 of DCPIP are
completely decolourised, dilute the fruit juice and repeat the test. If the fruit juice
has a strong colour that will interfere with determining the end point, dilute the
juice before testing.
h Calculate the amount of vitamin C in the standard solution in mg cm 3. Calculate
how much vitamin C there is in each of the fruit juices in mg cm 3.
Changes in method
Used a syringe rather than a burette
1ml of DCPIP was added to a 100cm3 beaker
Fruit juice was added using a burette until the DCPIP changed colour
Calculated the amount of vitamin c and fruit juice used to change the colour of the
DCPIP
Used a burette and was filled with a 50cm3 fruit juice sample
Analysis of results
Grapefruit has the largest amount of vitamin c, since it required the least amount of
juice to change the colour of the DCPIP
Kiwi had the least vitamin c, as we can see from the table that it required the most
amount of fruit juice to change the colour of the DCPIP
The results would have been more accurate if we repeated the experiment for each fruit
twice
