L7: Lipids' properties

P.7

Lipids Properties:

Lipids are a heterogeneous group of compounds synthesized by organisms that are present in all biological tissues. These compounds are characterized as natural substances that do not mix with water but dissolve in organic solvents. There are several classes of lipids including: fatty acids, waxes,triacylglycerols,phospholipids,terpens and steroids.
Like carbohydrate C,H and O are the principal elements of lipids although oxygen content is much reduced.
Lipids are made in general of long chains of hydrocarbons with relatively little oxygen. As a result of this, they tend to be non-polar, meaning that they do not dissolve in polar solvents such as water.
In this experiment we are going to test the solubility of different oils and how to identify lipids from a sample.


Objectives:

1- Test the solubility of lipids .
2- Identify lipids in liquids compouns
3- Understand what are an emulsion and the effect of detergents

Material:

Test tube rack
250 ml beaker
Water  90g
6 test tube
Cellullose paper
Dropper
Scissors
Glass road
Olive oli
Soap
Milk with differents fat content full-cream, semiskimmed and skimmed milk
Petroleum ether
Ethanol
Sudan III
Gogles
Google

Procedure:

Solubility of some lipids:

1- Clean and dry three test tubes.Label as W (Water) ethanol (E) and PE (ether)
2 Add 3 drops of oleic acid to small test tubes
3Add 1ml of  water in the first test tube(W)
4 Add 1ml of ethanol in the secone test tube(E)
5 Add1ml of petroleum ether in the third test tube (PE)
6 Shake carefully each test tube and record solubility and observations in your worksherret

Lipids identification

Transluced mark:

7 Cut  two pieces(10x10) of cellulose paper.
8 Put 1 drop of water in the first squared piece.You will see a translucent spot.Wit for a while and observere what happening.
9 Put 1 drop of olive oil in the second squared piece of cellulose paper. Your will see a translucent spot Wait for a while and observe what is happening.Has the spot disapperred?Why ?                           

  




Sudan III : Be careful Sudan red can stain clohes:


SudanIII is a red fat-soluble dyethat is utilized in the identification of the presence oflipids, triglycerids and lipopr4oteins in liquids
10 Take the W test tube of thefirst experiment and add 2 drop of SudanIII
11 Prepare four test tube: 3 with milk with differend fay content fat content (M1,M2,M3) and soda (S) .Add two drops of SudanIII and observe the results.

Permanents emulsion:

We put 100 mL of water in a 250 mL beaker. We have put 2mL oil and we have mixed. When we saw what was happening, we have put a few drops of soap and have seen the change.

Observations and results:

1. Solubility of some lipids
Oil and water didn't mix, oil formed micelles when it is mixed amb ethanol. And in the third test tube, ether (organic compound) dissolved oil. 

2.Transluced mark

When we added a drop of H2O on the cellullose paper it evaporated and leaves no mark. However,  the oil left a translucent mark and stayed on the paper.

3. SudanIII

Sudan III is a fat-soluble ink and dye black the oil sampl. Unfortunately, Sudan III didn't work, perhaps because it was very diluted. 

4.Permanent emulsion

When water an oil are mixed, and stir with a sitrring rod, they didn't mix. A monolayer of oil and water formed in the beaker. But when we added soap and we stir again, oil formed little micelles that didn't unite and a permanent emulsion was formed.

Questions :

1-From your observation, which compounds can dissolve lipids?
      1- First test tube :water and oil ,don't mixt 
      2-Firts test tube :oil and ethanol - oil formed micelles
      3- Firs tes tube:oil and ether - ether ( organic dissolvent) can disolvent

2-Do the oil and water mix? what can you conclude about the polarity of the oil if you know that water is polar?

 No, becose water is polar and the oil is non polar 

3- Why is liquid the olive oil at room temperature? and why not the lard?

   Oil has a lower point function as the carbon chain is shorter and lamantega to come from      animal fat carbon chain is longer and more difficult to breaK.

4- Why does a lipid leave a translucent spot on paper?

     Because fat oil does not evaporate the water instead if

5-  Which type of milk contains more lipids? why?

    Whole milk because it has more fat because the skimmed or semi skimmed Redi been    industrially fat content in milk

6-  Did the oil and water mix when you added the soap?

    Makes the water slide so fat formed by the oil disappear

7-  What did the soap do to the fat?

       The soap dissolves in oil miseles

8- Can you think about process and locations were compounds like the soap would be    important to an animal?

  Bile acids are part of the sterols are importan