Flash content link: https://vlab.amrita.edu/repo/BIOTECH/BIC/Estimation_%20saponification_value_oils_%20fats/index.swf
Procedure:
Materials Required:
1) Fats and Oils [coconut oil, sunflower oil]
2) Conical Flask
3) 100ml beaker
4) Weigh Balance
5) Dropper
6) Reflux condenser
7) Boiling Water bath
8) Glass pipette (25ml)
9) Burette
Reagents Required:
1) Ethanolic KOH(95% ethanol, v/v)
2) Potassium hydroxide [0.5N]
3) Fat solvent
4) Hydrochloric acid[0.5N]
5) Phenolphthalein indicator
Procedure:
1) Weigh 1g of fat in a tared beaker and dissolve in about 3ml of the fat solvent [ ethanol /ether mixture].
2) Quantitatively transfer the contents of the beaker three times with a further 7ml of the solvent.
3) Add 25ml of 0.5N alcoholic KOH and mix well, attach this to a reflux condenser.
4) Set up another reflux condenser as the blank with all other reagents present except the fat.
5) Place both the flasks in a boiling water bath for 30 minutes .
6) Cool the flasks to room temperature .
7) Now add phenolphthalein indicator to both the flasks and titrate with 0.5N HCl .
8) Note down the endpoint of blank and test .
9) The difference between the blank and test reading gives the number of millilitres of 0.5N KOH required to saponify 1g of fat.
10) Calculate the saponification value using the formula :
Saponification value or number of fat = mg of KOH consumed by 1g of fat.
Weight of KOH = Normality of KOH * Equivalent weight* volume of KOH in litres
Volume of KOH consumed by 1g fat = [Blank – test]ml
Differences Encountered In a Real Laboratory:
In an actual laboratory setting, there are certain important steps that are not necessarily applicable in a virtual lab.
- Always wear lab coat and gloves when you are in the lab. When you enter the lab, switch on the exhaust fan and make sure that all the reagents required for the experiment are available. If they are not available, prepare the reagents using the components shown in the reagent preparation.
- Care should be taken while handling reagents like potassium hydroxide and hydrochloric acid. Accidental spills of these reagents will cause a severe itching sensation. Wash the affected area with cold water and inform the lab assistant immediately.
- Caution should be taken while attaching the reflux condensors to the conical flask.
- Make sure that the waterbath is set to 100 degree celsius and the reflux condensors are set with proper settings before starting the experiment.
- The endpoint point of titration should be carefully observed as the disappearance of pink colour to white color.
- After the experiment, switch off the waterbath and carefully remove the reflux condensors.
- After completing the experiment, clean the glassware and wipe the lab bench.
- Switch off the exhaust fans.
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