Name: Hiba Majid (P:\Science\Mr Alim\Year 12\AS Biology)
QUESTION TO BE INVESTIGATED: Which juice contains the largest amount of Vitamin C?
SCIENTIFIC RESEARCH (REFERENCED):
● Vitamin C helps to protect cells by acting as an antioxidant, which stops damage caused by free
radicals. (Cabello, 2009) It is also necessary for the maintenance of healthy connective tissue: it gives
support and structure for other tissue and organs and helps it to heal when wounded.
● Deficiency of vitamin C can lead to scurvy with the symptoms including anaemia, exhaustion,
spontaneous bleeding, pain in limbs and swelling in parts.
● Humans cannot make their own vitamin C and so require an outside source via consuming fruits and
vegetables containing vitamin C. (Maxfield and Crane, 2022)
● Citrus fruits are near the top of the list for vitamin C-rich foods. Eight ounces of fresh-squeezed
orange juice has nearly 125 milligrams of vitamin C. (Anne, 2022)
● If vitamin C, which is a good reducing agent, is present, the blue dye in DCPIP, which turns pink in acid
conditions, is reduced to a colourless compound by ascorbic acid. This reaction is a redox reaction:
vitamin C (ascorbic acid) is oxidised to dehydroascorbic acid, and DCPIP is reduced to the colourless
compound DCPIPH2 (Dichlorophenolindophenol - Wikipedia, 2022)
● 2,6-dichlorophenolindophenol (DCPIP) is a compound that is often used as a redox dye. Oxidised
DCPIP is blue, DCPIPH, which is reduced by a single electron, is pink, and fully reduced DCPIP is
colourless. (Why does dcpip turn colourless?, 2022)
● How to calculate concentrations: concentrations tell us the mass of a solute in a given solution. the
units are g/dm3 (Freesciencelessons, 2022)
● In order to find the mass of 1% vitamin C required to decolourise 1cm³ of DCPIP, you do 10mg ×
volume of vitamin C used, which is what we find using our standard.
● In order to find the mass of vitamin C in a fruit juice sample, we take the mass of vitamin C to
● decolourise 1cm³ of DCPIP and divide this by volume of sample required to decolourise 1cm³ of DCPIP
HYPOTHESIS: Orange juice will have the highest vitamin C content out of the juices.
METHOD:
Piece of apparatus Purpose of piece of apparatus How piece of equipment was used Appendix 5c
accurately/appropriately/ safely technique
DCPIP solution Acts as indicator for colour The DCPIP may act as an irritant to skin and
change eyes and may cause staining. To avoid
damage, you should wear eye protection
and to reduce chances of spillage, it should
be kept away from the edge of the desk.
(Low-medium risk, if in eyes or skin)
test tubes To hold the solutions of fruit If the test tubes break, there will be broken
juices in glass, which can lead to cuts from sharp
objects. You should therefore keep away
from the edge of the desk. (Low-medium
risk)
1 ml Pipette To accurately measure 1 cm 3 For higher accuracy, you can go down at eye
of DCPIP solution level to ensure the correct amount is being
used. (Low risk)
Mr Alim
QUESTION TO BE INVESTIGATED: Which juice contains the largest amount of Vitamin C?
SCIENTIFIC RESEARCH (REFERENCED):
● Vitamin C helps to protect cells by acting as an antioxidant, which stops damage caused by free
radicals. (Cabello, 2009) It is also necessary for the maintenance of healthy connective tissue: it gives
support and structure for other tissue and organs and helps it to heal when wounded.
● Deficiency of vitamin C can lead to scurvy with the symptoms including anaemia, exhaustion,
spontaneous bleeding, pain in limbs and swelling in parts.
● Humans cannot make their own vitamin C and so require an outside source via consuming fruits and
vegetables containing vitamin C. (Maxfield and Crane, 2022)
● Citrus fruits are near the top of the list for vitamin C-rich foods. Eight ounces of fresh-squeezed
orange juice has nearly 125 milligrams of vitamin C. (Anne, 2022)
● If vitamin C, which is a good reducing agent, is present, the blue dye in DCPIP, which turns pink in acid
conditions, is reduced to a colourless compound by ascorbic acid. This reaction is a redox reaction:
vitamin C (ascorbic acid) is oxidised to dehydroascorbic acid, and DCPIP is reduced to the colourless
compound DCPIPH2 (Dichlorophenolindophenol - Wikipedia, 2022)
● 2,6-dichlorophenolindophenol (DCPIP) is a compound that is often used as a redox dye. Oxidised
DCPIP is blue, DCPIPH, which is reduced by a single electron, is pink, and fully reduced DCPIP is
colourless. (Why does dcpip turn colourless?, 2022)
● How to calculate concentrations: concentrations tell us the mass of a solute in a given solution. the
units are g/dm3 (Freesciencelessons, 2022)
● In order to find the mass of 1% vitamin C required to decolourise 1cm³ of DCPIP, you do 10mg ×
volume of vitamin C used, which is what we find using our standard.
● In order to find the mass of vitamin C in a fruit juice sample, we take the mass of vitamin C to
● decolourise 1cm³ of DCPIP and divide this by volume of sample required to decolourise 1cm³ of DCPIP
HYPOTHESIS: Orange juice will have the highest vitamin C content out of the juices.
METHOD:
Piece of apparatus Purpose of piece of apparatus How piece of equipment was used Appendix 5c
accurately/appropriately/ safely technique
DCPIP solution Acts as indicator for colour The DCPIP may act as an irritant to skin and
change eyes and may cause staining. To avoid
damage, you should wear eye protection
and to reduce chances of spillage, it should
be kept away from the edge of the desk.
(Low-medium risk, if in eyes or skin)
test tubes To hold the solutions of fruit If the test tubes break, there will be broken
juices in glass, which can lead to cuts from sharp
objects. You should therefore keep away
from the edge of the desk. (Low-medium
risk)
1 ml Pipette To accurately measure 1 cm 3 For higher accuracy, you can go down at eye
of DCPIP solution level to ensure the correct amount is being
used. (Low risk)
Mr Alim
