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Questions and Answers
What is the primary aim of using the Fehling method in the quantitative analysis of carbohydrates?
What is the primary aim of using the Fehling method in the quantitative analysis of carbohydrates?
- To determine the grams of glucose dissolved in the solution (correct)
- To identify the presence of reducing sugars other than glucose
- To evaluate the total carbohydrate content in a sample
- To measure the concentration of fructose in the solution
Why is it essential to heat the Fehling reagent to a temperature of 70-80°C instead of boiling?
Why is it essential to heat the Fehling reagent to a temperature of 70-80°C instead of boiling?
- To ensure maximum solubility of glucose
- To enhance the reactivity of the reagents used
- To prevent the evaporation of water from the solution (correct)
- To control the viscosity of the reagent mixture
In the calculation of glucose concentration, what does 'E.P' represent?
In the calculation of glucose concentration, what does 'E.P' represent?
- Estimated precision of the reagents
- Excess glucose present in solution
- Error percentage in measurements
- End point of the titration (correct)
What is the expected outcome at the end point of the titration using the Fehling method?
What is the expected outcome at the end point of the titration using the Fehling method?
Which of the following correctly represents the relationship between glucose amount and solution volume as per the calculation provided?
Which of the following correctly represents the relationship between glucose amount and solution volume as per the calculation provided?
Flashcards
Fehling method
Fehling method
A chemical method used to estimate the amount of sugar (glucose) in a solution.
Fehling reagent
Fehling reagent
A solution used to quantitatively estimate the amount of glucose present in a solution. It’s composed of two parts: Fehling A and Fehling B.
End point
End point
The point in a titration when a noticeable change indicating the completion of a reaction occurs.
Titration
Titration
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Glucose estimation
Glucose estimation
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5ml Feh = 0.067gm glucose
5ml Feh = 0.067gm glucose
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Calculation of glucose concentration
Calculation of glucose concentration
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Procedure steps
Procedure steps
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Study Notes
Qualitative Analysis of Carbohydrates
- Aim: Determine the grams of glucose in solution using Fehling's method.
Fehling's Method Procedure
- Step 1: Prepare Fehling's reagent; combine 2.5ml of Fehling A and 2.5ml of Fehling B, and 5ml total.
- Step 2: Heat the solution to 70-80°C on a hotplate. Heat gently to avoid boiling, preventing water evaporation.
- Step 3: Titrate the solution against the sugar solution.
- Step 4: The endpoint is when the mixture turns a reddish-brown precipitate.
- Step 5: Repeat the titration three times and average the results.
Calculations
- 5ml Fehling reagent equals 0.067g of glucose
- End point of the titration corresponds to 0.067g glucose
- To find the amount of glucose in 100ml of solution, use the formula X = (0.067 x 100)/End Point, where X equals the amount of glucose in grams per 100ml.
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