Podcast
Questions and Answers
What is the aim of the Fehling method in sugar estimation?
What is the aim of the Fehling method in sugar estimation?
- To calculate the pH level of glucose solutions
- To determine the boiling point of water
- To identify different types of carbohydrates
- To measure the concentration of sugar in a solution (correct)
Why should the Fehling reagent not be boiled during the heating process?
Why should the Fehling reagent not be boiled during the heating process?
- To increase the reaction rate of the titration
- To allow for better color change detection
- To avoid the formation of toxic gases
- To prevent the evaporation of water from the solution (correct)
What is the end point indicator when performing the titration with Fehling's reagent?
What is the end point indicator when performing the titration with Fehling's reagent?
- A yellow solid precipitate
- A clear solution with no precipitate
- A blue color change
- A reddish brown precipitate (correct)
How much glucose corresponds to 5ml of Fehling solution?
How much glucose corresponds to 5ml of Fehling solution?
What formula is used to calculate the amount of glucose in 100ml of solution from the end point?
What formula is used to calculate the amount of glucose in 100ml of solution from the end point?
Flashcards
Fehling method
Fehling method
A chemical method used to estimate the amount of glucose in a solution.
Fehling reagent
Fehling reagent
A solution used in the Fehling method to detect reducing sugars.
Reducing Sugars
Reducing Sugars
Sugars that can reduce Fehling's reagent
Titration endpoint
Titration endpoint
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Glucose estimation
Glucose estimation
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5ml Fehling reagent
5ml Fehling reagent
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Calculation for glucose
Calculation for glucose
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Heating conditions
Heating conditions
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Study Notes
Quantitative Analysis of Carbohydrates
- Aim: Determine the grams of glucose dissolved in a solution using the Fehling method.
Procedure
- Step 1: Prepare the Fehling reagent by mixing 2.5ml of Fehling A and 2.5ml of Fehling B with 5 ml of distilled water
- Step 2: Heat the solution on a hot plate to 70-80°C
- Note: Do not heat to boiling to prevent water evaporation from the solution
- Step 3: Titrate the sugar solution with the Fehling reagent
- Step 4: Record the endpoint, which is a reddish-brown precipitate.
- Step 5: Repeat the process three times and calculate the average value.
Calculation
- 5ml of Fehling reagent equals 0.067g of glucose
- The endpoint of the titration is equivalent to 0.067g of glucose
- 100ml of solution containing Xg of glucose
- X = (0.067 x 100)/endpoint value (in ml) = g per 100ml of sugar solution
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