Why do you need to use excess Benedict's reagent if you want to get an idea of concentration of sugar solution?
Answers
Since you are testing for concentration you need to keep the volume of the unknown concentrations equal.
For example if you have test tube A and B, you should fill each with 10 ml of the different concentrations.
You then add excess Benedict's solution in each of the test tubes.
Reason : In order to see changes occurring due to the sugar concentration.
Note : the changes do not occur due to the Benedict's solution but the sugar concentration.
The excess Benedict's solution also drives the reaction to completion in a relatively short period of time.
Benedict's reagent is a re-agent that uses the change of colour (blue to red) to identify the presence of a group of carbohydrates that we collectively known as Reducing Sugars.
The re-agent has a copper in its plus 2 oxidation state in the form of copper citrate. T
he copper can oxidize certain sugars known as aldoses, which have a minimum one available aldehyde group that can be oxidized to a carboxylic acid practical group.