Commercial Vitamin C Tablets - Analysis
Analysis of Commercial Vitamin C Tablets
Aim: To employ iodometric titration to determine the content of vitamin C in commercial tablets using volumetric analysis and compares it with the manufacturersÂ’ specifications.
Introduction
Vitamin C is an essential substance for maintaining good health and it is proved to be the agent which prevents scurvy. Most animals can synthesize their own vitamin C, but some, such as human cannot. Owing to the increasing concern for oneÂ’s health since the last century, vitamin C tablets become the most popular supplyment to normal diets.
[IMAGE]In this experiment, the vitamin C content of a commercial tablet is determinded and compared with the maunfacturersÂ’ specification. Vitamin C is water-soluble and is an enantiomer of ascorbic acid. (Commercial vitamin C is often a mixture of ascorbic acid and other ascorbates.) Ascorbic acid, C6H8O6, is a reducing agent that reacts rapidly with iodine (I2) in acidic medium to produce iodide ion (I-) and dehydroascorbic acid, as shown in the following equation: [IMAGE]
+ I2(aq) -----------> + 2H+(aq) + 2I-(aq)
Ascorbic acid (Vit. C) Dehydroascorbic acid
However, since iodine is only slightly soluble in water, ascorgic acid should not be titrated directly by a standard iodine solution, since the end point of titration is not o obvious. Instead, back titration will be employed.
The titration of a reducing agent with iodine to produce iodide ion is referred to as an iodometric titration. Iodine is generate by adding a weighed amount of standard potassium iodate (KIO3) to an excess of potassium iodide (KI) and then add adding strong dilute sulphuric acid
(H2SO4) to produce iodine as shown below:
(1) KIO3(aq) + 5KI(aq) + 3H2SO4(aq) → 3I2(aq) + 3H2O(l) + 3K2SO4(aq)
The known excess of I2 generated by the reaction is immediately reacted with the ascorbic acid sample; finally, the excess unreacted iodine is
Aim: To employ iodometric titration to determine the content of vitamin C in commercial tablets using volumetric analysis and compares it with the manufacturersÂ’ specifications.
Introduction
Vitamin C is an essential substance for maintaining good health and it is proved to be the agent which prevents scurvy. Most animals can synthesize their own vitamin C, but some, such as human cannot. Owing to the increasing concern for oneÂ’s health since the last century, vitamin C tablets become the most popular supplyment to normal diets.
[IMAGE]In this experiment, the vitamin C content of a commercial tablet is determinded and compared with the maunfacturersÂ’ specification. Vitamin C is water-soluble and is an enantiomer of ascorbic acid. (Commercial vitamin C is often a mixture of ascorbic acid and other ascorbates.) Ascorbic acid, C6H8O6, is a reducing agent that reacts rapidly with iodine (I2) in acidic medium to produce iodide ion (I-) and dehydroascorbic acid, as shown in the following equation: [IMAGE]
+ I2(aq) -----------> + 2H+(aq) + 2I-(aq)
Ascorbic acid (Vit. C) Dehydroascorbic acid
However, since iodine is only slightly soluble in water, ascorgic acid should not be titrated directly by a standard iodine solution, since the end point of titration is not o obvious. Instead, back titration will be employed.
The titration of a reducing agent with iodine to produce iodide ion is referred to as an iodometric titration. Iodine is generate by adding a weighed amount of standard potassium iodate (KIO3) to an excess of potassium iodide (KI) and then add adding strong dilute sulphuric acid
(H2SO4) to produce iodine as shown below:
(1) KIO3(aq) + 5KI(aq) + 3H2SO4(aq) → 3I2(aq) + 3H2O(l) + 3K2SO4(aq)
The known excess of I2 generated by the reaction is immediately reacted with the ascorbic acid sample; finally, the excess unreacted iodine is