1. Give a generalization of solubility of lipids. 2.Define a. Emulsification b. Rancidity 3. is the importance of the acrolein test? Write a balance equation for this test 4. Differentiate
1. Give a generalization of solubility of lipids. 2.Define a. Emulsification b. Rancidity 3. is the importance of the acrolein test? Write a balance equation for this test 4. Differentiate the two types of rancidity. 5. is the importance of emulsification in digestion of lipid? 6. is the positive result and the importance of Liebermann-Burchard and Salkowski tests? Transcribed Image Text: 2. Translucent spots – Place 1 drop of coconut oil on a piece of ordinary writing
paper. Note the formation of a semi-transparent spot. Allow to evaporate
spontaneously. Observe what happens to the transparent spot. Repeat using
glycerol instead of coconut oil.
3. Acrolein Test – Place 5 drops of coconut oil in a test tube. Add a few crystals of
KHSO, and heat. Observe change in color and odor evolved. Repeat using
glycerol and oleic acid instead of coconut oil.
4. Test for Unsaturation – Prepare 3 test tube. To the first add 10 drops coconut oil,
to the second, add 10 drops oleic acid, the third a few crystals of palmitic acid.
Add 1 ml of 0.05M KMNO, and 1 ml of 10% Na,CO. Shake the mixture and
allow to stand for a few minutes with occasional shaking. Observe the color of the
5. Test for Rancidity – Prepare 3test tubes and add 5 drops of fresh coconut oil to
each tube. To the first tube , add 2 drops phenolphthalein, to the second 1 drop
methyl orange, and to the third place a piece of blue and red litmus paper. Repeat
using rancid oil instead of fresh coconut oil.
6. Emulsification – Prepare 3 test tubes and add 1 ml of coconut oil to each. To the
first tube, add 5 drops of bile solution, to the second 5 drops albumin and to the
third 5 drops soap solution. Shake each mixture very well and compare results.
7. Liebermann-Burchard Test – Dissolve 0.5 g of cholesterol in 2 ml chloroform and
place in an evaporating dish. Add 1 ml acetic anhydride and 5 drops of conc.
Sulfuric acid. Mix and place in the dark for 10 minutes. Observe color change.
8. Salkowski Test – Dissolve 0.5 g of cholesterol in 2 ml of chloroform. Allow 1 ml
of conc. Sulfuric acid to flow along the side of the tube avoiding the mixture with
chloroform layer. Note color produces both in the chloroform and sulfuric acid
layers. Transcribed Image Text: АСTIVITY NO. 5
REACTION OF LIPIDS
Lipids are heterogeneous class of bioorganic compounds which includes fats
and oils, waxes, cholesterol and its derivatives, some vitamins and prostaglandins.
these substances have in common is their limited solubility in water.
Fats and oils are the most abundant lipids found in nature. Both are
triacylglycerol mixtures. Fats contain higher percentage of saturated fatty acid while
oils have more of the unsaturated fatty acids.
The chemical properties of triacylglycerol are typical with that of esters and
alkanes. Important reactions of these compounds are hydrolysis, saponification,
hydrogenation and rancidity and emulsification.
Hydrolysis may occur making them acidic giving rise to volatile fatty acid
which undergoes oxidation to give foul odor of volatile aldehydes and ketones.
Objectives: At the end of the activity, the student can:
1. List some chemical properties of lipids.
2. Identify the best solvents for lipids.
3.Test the different components of lipids.
4. Differentiate rancid from fresh oil using different indicators.
Reagents: 5 ml Coconut oil, 1 ml diethylether, 1 ml-5% HCI, 1 ml-5% NaOH, 1 ml
ethyl alcohol, 1 ml benzene, 1 ml CCl, 1 ml distilled water, 5 ml
chloroform, blue and red litmus paper, 3 drops phenolphthalein, 3 drops
methyl orange, few crystals KHŠO,drops albumin, 1 g cholesterol, 1 ml
acetic anhydride, 1.5 ml conc. H,SO4, 1 ml glycerol, palmitic acid, 2 ml
oleic acid, 3 ml- 0.05M KMNO, solution, 3 ml-10% Na.CO,
BRING: bile solution, soap solution
Materials:10 ( 20ml Test tubes), test tube rack, test tube brush, test tube holder, 6
dropper, 10 ml graduated cylinder, evaporating dish, platform balance,
alcohol lamp, spatula
1. Solubility – Place 1 ml of distilled water, 5% HCI, 5% NaOH, diethyl ether, CCl.,
ethyl alcohol, chloroform, into 7 different test tubes. Add 1 drop of coconut oil and
shake. Observe solubility of oil in the different solvents.
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