Preparation of Standard Volumetric Solutions
1. 0.1N Sodium thiosulphate solution
Reagents: Sodium thiosulphate crystals, Potassium dichromate (primary standard NIST certified), Sulphuric acid, Potassium iodide , Starch Solution (1%): Weigh 1g of soluble starch and mix it with 100ml of boiled water.
Procedure
• Weigh 25 g of sodium thiosulphate crystals and transfer it in a 1000 ml volumetric flask.
• Dissolve it in minimum amount of distilled water and make up the volume to 1000 ml.
Standardization of the prepared Sodium thiosulphate solution as follows:
• Weigh 0.125 g of dry Potassium dichromate (K2Cr2O7) and transfer it into an iodine flask. Dissolve it in minimum amount of distilled water.
• Add 10 ml of Sulphuric acid and then 10 ml
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• Continue the titration until the colour changes sharply from blue to light green. Repeat the titration two more times.
• Calculate the normality of sodium thiosulphate solution on the basis of normality of potassium dichromate.
Observations and Calculations:
Normality of Sodium Thiosulphate (Na2S2O3) = Wt of K2Cr2O7 × 1000 Vol of 0.1 N Na2S2O3 solution used × 49.03 S. No. Weight of Potassium dichromate
(g) Volume of 0.1 N Sodium thiosuphate solution used
(ml) Normality of Na2S2O3
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S. No. Wt of empty dish, W (g) wt of (sample + dish) before drying ,W1 (g) wt of (sample + dish) after drying ,W2 (g) Moisture % Average
1 73.5172 76.5891 76.2216 11.96%
11.66%
2 77.1345 79.3092 79.0619 11.37%
Result
The percentage of moisture content determined in Chana dal is 11.66% .
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EXPERIMENT 3
Aim: To determine the fat content in food sample by Soxhlet extraction method.
Introduction
The crude fat content can be conveniently determined in foods by extracting the dried and ground material with petroleum ether or diethyl ether in Soxhlet extraction apparatus.
Principle
Extraction of the crude fat is carried out either with petroleum ether or diethyl ether in a Soxhlet unit followed by volatilization of the solvent after extraction and determination of the mass of the residue.
Apparatus Required
Soxhlet apparatus
Reagents
Diethyl Ether -anhydrous or Petroleum ether (b.p. 60-80°C)
All standardizations are performed in triplicate. Weigh out .1000-.1200 gram KIO3. Add 70-80 mL of deionized water. Swirl and dissolve. Add 3 mL of 6M HCl. Swirl and mix. Quickly titrated the brow-red solution with 0.1M Na2S2O3 until it is light yellow. Then add 3.5 mL of starch indicator. Titrate again until the dark color first disappears.
6. Pour the salt solution into a clean tall glass so that the liquid level is 1/4 inch (0.5 cm).
First I will set up the apparatus as show above. I will add 1.5 grams
The first step that needed to be done in this experiment was adding hydrochloric acid (HCl)
Add 3 drops of iodine solution * Shake it well,
Next, obtain a 96 well plate and take 1 sample of 190 μl from the blank and put it in well #A1. Then take 3 different 190 μl samples of concentration 0 and put it in Wells F2, G2, and H2. Repeat this step again by taking 3 more different 190 μl samples of concentra-tion 1 and putting it in wells F3, G3, H3. It should be noted that it is important to vortex each
Prepare standard solution #1, Take 1 ml sub stock solution from the 100 ml beaker and then put into 25 ml volumetric flask with the help of 10ml graduate pipette.
40 g of ice and approximately 30 ml of sulfuric acid is cautiously added to a 100 mL beaker respectively. Weigh 7.6 g of ammonium chloride and 14.0 g of ammonium bromide and place it in another beaker, crushing the lumps until a powdery mixture remains. The powdery mixture is then transferred to a 125 mL Erlenmeyer flask. Add the ammonium salts into the sulfuric acid mixture. Heat is applied to dissolve the salt. Once the
Place 100 ml of distilled water in a 250-ml (or 400-ml) beaker. Add 1.26g of oxalic acid dihydrate (H2C2O4.2H2O) and 1 ml of concentrated ammonia. Stir the mixture until the solid has dissolved completely.
XII. Take the 250 ml beaker to your lab bench. Set up a gravity filtration with a plastic funnel, folded wet filter paper, and an Erlenmeyer flask. Pour the content in the 250 ml beaker slowly through the filter paper. Wash the filter paper with deionized water. Dispose of the filtrate in the proper labeled waste container.
2) Rinse the solid with about 30 mL of distilled water and decant the liquid from the solid. It is critical that as little solid as possible is lost during this process. Repeat the rinsing two or three times.
1. 10 drops of 1 M K2CrO4 was added to the solution and stirred for about 10 minutes.
2. Add about 20 mL of distilled water and stir the mixture with a glass stirring rod to dissolve the sample. There may be a small amount of insoluble residue. If your sample does not dissolve completely, remove the insoluble material by filtration.
Add 4 drops of phenolphthalein in to the prepared acetic acid, and check whether the color changes to dark pink.
1. Number four clean test tubes 1-4. 2. Place 1 ml (or 20 drops) of the following solutions into each tube: water, egg albumin, starch, and chicken broth. 3. Add 3 drops of Buiret reagent to each tube and gently shake