LIPIDS PROPERTIES

Introduction:
Lipids are heterogenous 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
• Trepens ans steroids. 

Material:
Test tub rack
250mL beaker
Water
6 test tubes
Dropper
Scissors
Glass rod
Olive oil
Soap (detergent)
Ethanol 
Sudan III


Objectives: 

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

Procedure: 
Solubility of some lipids:

Clean and dry three test tubes. Label as W (water), ethanol (E) and PE (ether)
Add 3 drops of oleic acid to 3 small test tubes. 
Add 1 ml of water in the first test tube (W)
Add 1 ml of ethanol in the second test tube (E). 
Add 1 ml of petroleum ether in the third test tube (PE). 
Shake carefully each test tube and record solubility and observations in your worksheet. 

Lipids identification:
Translucent mark:

Cut two pieces (10x10) of cellulose paper. 
Put 1 drop of water in the first squared piece. You will see a translucent spot, wait for a while and observe what is happening. 
Put 1 drop of olive oil in the second squared piece of cellulose paper. You will see a translucent spot. Wait for a while and observe what is happening.

Sudan III dye: BE CAREFUL SUDAN RED CAN STAIN CLOTHES!!!!

Sudan III is a red fat-soluble dye that is utilitzed in the identification of the presence of lipids, triglycerides and lipoproteins in liquids. 

Take the W test tube of the first experiment and add 2 drops of Sudan III 
Prepare four test tubes: 3 with milk with different fat content (M1, M2, M3) and soda (S). Add two drops of Sudan III.




PERMANENT EMULSION: 

Take a 250ml beaker and put 100ml of water. 
Add 1ml of olive oil. With a glass rod stir the mixture vigorously and let it stand for a few minutes. 
Make note of what is happening. 
Add 2 drops of soap and stir the mixture again. Let it stand for a few minutes and notice the differences between both mixtures.

STARCH

Introduction: 

We will see in different types of food if they have starch or not. The aliments are potato, frankfurt and jam. But in the first part of the experiment we work with a leaf.

Material:

- Bunsen burner
- Tripod Stand
- Wire gauze
- 250 cm3 beaker
- Boiling tube
- Forceps
- Test tube Holder
- Leaf to be tested
- 90% ethanol
- Iodine/potassium iodine solution

Objectives: 

1. Identify the presence of starch in leaves.
2. Relate the presence of starch with photosynthesis.
3. Identify the presence of starch in some food.

Procedure: 

This experiment we divide in two parts: the leaf and the 3 aliments

First Part: Leaf

We start remove a green leaf from a plant that has been exposed to sunlight for few hours.

Half-fill a 250cm3 beaker with water. We heat the water until it boils and keep the water at boiling point. Then we use the forceps to place the leaf in the boiling water. Boil for 2 minutes. (Turn off the bunsen burner) Place boiled leaf in a boiling tube containing 90% ethanol and later place the boiling tube in hot water and boil for 10 minutes or until the leaf decolourizes. (It may be necessary to replace the ethanol). Gently we remove the leaf and wash with a fine trickle of cold tap water. We spread the leaf evenly on a white tile an finally we add a few drops of iodine/potassium iodine solution to the leaf and note what happens.

QUESTIONS

1. The fotosintesi

2. CO2 + H20 --> C6H12O6

3. The leaf lose the turgent condition

4. The chlorophyll disappear. It doesn't have colour.

5. Because the sugar isn't soluble with ethanol





Second Part: Aliments

Material:
- Jam
- Frankfurt
- Potato
- Knife
- 3 watch glass
- Iodine


Procedure:
We put the 3 aliments in differents watch glasses. Then we cut the frankfurt in two parts, cut a small piece of potato. With the dropper, put the iodine in each aliment. Finally we compare the result.

Observations:
The potato is more black than the others, this significate that the potato have more starch than frankfurt and jam.

FEHLING'S TEST: REDUCING SUGARS

Introduction: 
Fehling's solution is a chemical test used to differentitate between reducing and non-reducing sugars. This test is based on the reaction of a functional group of sugar molecules with Fehling's reagent.

Fehling's reagent has to separate solutions: Fehling's A and Fehling's B.
Fehling's A: is a blue aqueous solution of copper (II) sulphate.
Fehling's B: clear and colourless solution of potassium sodium tartrate and sodium hydroxide.

Material:

-Test Tube rack

-10ml Pipet

-Distilled Water

-5 test tubes

-5 spatula

-Lactose

-Maltose

-Glucose

-Sucrose

-Starch

-Fehling's A and B solutions

-HCl

Objectives: 

1. Identify reducing sugars.
2. Comprehend redox reactions.
3. Understand the relation between structure and reducing ability of some sugars.

Procedure: 

First, we take 5 test tubes and label: G, M, S, L, ST. Then we put 2mL of water inside each tube and with different spatulas put a small amount of each sugar and it dissolve. Later, add 2mL of Fehling's A and solution and then Fehling's B. Place each test-tube in a boiling water bath and finally observe what is happening.

Starch Hydrolysis

Hydrolysis is the reaction of a commpound of with water.

We place 2mL of 1% starch in a test tube and add 0.5mL of 3M HCl. We mix and place this mixture in a boiling water bath for 10 minutes.

After 10 minutes, remove the tube from the water bath and let it cool. 

Neutralize this solution with 1M NaOH and mix well. Later, transfer 10 drops of this solution to a small test tube and add 1mL of Fehling's A solution and 1mL of Feghling's B. 

Finally, heat for a few minutes in a boiling water bath and record your observations. Compare the results of this test with your results for unhydrolyzed starch in the step 1 of this experiment.

QUESTIONS

1. The asymetric carbon

2. 

3. 

4. Give electrons to feeling reagent

Saccharides Properties

Introduction: 
Saccharides are organic molecules consisting of C, H and O atoms. Usually the empirical formula is Cn H2n On. Are divided into three groups:

• Monosaccharides
• Oligosaccharides
• Polysaccharides

Material:

-Test Tube rack

-10ml Pipet

-Distilled Water

-5 test tubes

-1 dropper

-5 spatula

-Lactose

-Maltose

-Glucose

-Sucrose

-Starch

-Lugol's iodine

Objectives: 

1. Identify different sugars from it's properties
2. Differentiate mono and disaccharides
3. Understand the relation between structure and some properties

Procedure: 

In the firts part of the experiment we are going to test some physical properties of the saccharides we have in the lab: flavour, crystal structure and colour.
Flavour: Put a small amount of each saccharide in our hand and taste it.
Crystals: Observe a small amount of each saccharide on a clock glass under magnification.
Colour: White, transparent or creamy.

To test solubility

We clean and dry 5 test tubes and label them "G, M, L, SU, S"
We put 5mL of water in each test tube
With the aid of a spatula, we put a small amount of each saccharide inside the labelled test tube and test if they are soluble or insoluble.
Finally, we observe if each saccharide forms a mixture called dissolution or a colloidal suspension.

Lugol's iodine Test

Add 2 drops of Lugol's iodine to each test tube and test if the reaction is positive or negative. The reaction is positive when iodin ereacts by turning from yellow to a purple, dark-blue/black colour.



















(DANIA'S BLOG PICTURE)

Egg experiment

Introduction: 

Molecules through a semi-permeable membrane into a region of higher solute concentration. Water molecules travel through the plasma membrane in order to equilibrate the intra and extra cellular concentrations.

Material:

-Egg

-Distilled Water

-600mL Beaker

-Knife

-Spatula

-Vinegar

Objectives: 

1. Know about the osmosis phenomena.
2. Understand the process of osmosis in plasmatic membranes

Procedure:
We divide this experiment in two days

First Day:
We take a 600mL beaker and put inside the egg. Lately, we cover the egg with vinegar and see the first result. The spatula help to dive the egg in the vinegar. When the egg shell dissolves we change the vinegar for distillated water. Before we change the vinegar we have to clean the beaker. We note the volume of solution than we put inside the beaker. (The egg absorbes some water and it enlarges)

Second Day:
In the second day, we observe the results and we see the egg bigger than the first day. This process is called turgor pressure.