L8: SAPONIFICATION

L8: Saponification

1. Introduction

Saponification is a reaction with a fatty acid with a strong base resulting in a salt of fatty acid soap is called.

This reaction is very important because the fatty acid are insoluble in water, but the soap molecule form micelles which make colloidal dispersions are believed.

2. Objectives

Our goal with our practice is to create a bar of soap.

3. Material

• 2 beakers of 250 mL
• watch galss
• spatula
• stirring rod
• caustic sosa
• water
• oil
• balance

4.Procedure

First of all, we have taken a 250 ml beaker and we put 90 mL of water, we put another beaker 270 mL of oil on a watch glass we put 32 grams of caustic soda.

We put the water i caustic soda and we mixed with a crowbar and we saw that was exothermic. Then we added the oil and we have mazclado until it has been a little more solid. In addition we have added an aroma.

(paula's blog)

5. Observations

We observed as the mixture of oil, water and caustic soda, has obtained a more solid form.

6. Conclusions

With the mix that we miss, we get soap and let it stand to harden i take shape.

L7: LIPIDS PROPERTIES

L7: Lipids properties

1. Introduction

Lipids are a heterogeneous group of compounds synthesized by organisms that are present in all biological tissues.

Like carbohydrates C,H and O are the principal elements of lipids althought oxygen content is much reduced.

 Lipids are made in general of long chains of hydrocarbons with realtively little oxygen. As a reault os this, they don't dissolve in polar solvents such as water.

In this experiment we are going to test solubility of different oils and how to identify lipids from a sample.

2. Objectives

• Test the solubility of lipids.
• Identify lipids in liquids compounds.
• Understand what are an emulsion and the effects of detergents.

3. Hypotesis

The hypothesis is to differentiate the reaction of water with different solutions.

4. Material

• test tube rack
• 250mL beaker
• water
• 6 test tubes
• cellulose paper
• dropper
• scissors
• glass road

• Olive oil
• soap
• milk with different fat content
• petroleum ether
• ethanol
• sudan III

5. Procedure

Solubility of some lipids:

First of all, we took 3 tubes test and we labeled them to differentiate which would have water, ethanol and ether. Each test tube we added 3 drops of oleic acid, then we put 1 mL of water, ethanol or ether according to the test tube.

Lipids identification:

       -  Translucent mark:

We caught two pieces of cellulose paper and we put a drop of water in one and on the other a drop of olive oil.

        - Sudan III dye:

We have prepared three test tubes with milk plus test water tube with the previous year, each test tube with a different milk (whole, semi-skimmed and without lactose), and we've put a drop of sweat III.

Permanent 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.

6. Observations

In the first part we have seen that oil is insoluble in water. When ethanol is in contact with oil, it from micelles and ether can dissolve oil.

In the second part we have identifed the oil from a drop on a cellulose paper.

In the thord part we have tried to identify lipids with sudan III dye. Unfortunately this part of experiment didn't work.

In the fourth part we wanted to see how soh oil. When we added oil to water, it forned a monolayer in the sufare. When we added soap, molecules of oil are dispersed throughout the solution.

7. Conclusion

We can conclude that:

1. Oil is soluble in organic compounds like ether and insoluble in water.
2. Sudan III stairs lipids.
3. Lipids leave a translucent spot in cellulose paper.
4. When soap is added in a water and oil mixture, the soap molecules disperse oil throught the solution (permanent emulsion).

8. Questions

1. From your observation, which compounds can dissolve lipids?

The ether can dissolve the lipids.

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

The oil is not soluble in water and remains in the top of the solution.

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

Because the oil has a melting point much lower melting, since the chain C is smaller.

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

because it is greasy, contains lipids.

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

Whole milk because it contains all lipids having milk.

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

It produces a permanent ebulltion.

7. What did the soap do to the fat?

That can not join again.

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

Bile acids.

L6. FEHLING'S TEST: REDUCING SUGARS

L6: Fehling's test: reducing sugars

1. Introduction

Fehling solution is a chemical test used to differentiate between reducing and non-reducing sugars. 

Fehling's reagent has two separate solutions: Felhing A and felhing's B.

Felhing's A: is a blue aqueous solution of copper (II) sulphate.

Felhing's B: clear and colourless solution of potassium sodium tartrate and sodium hydroxide.

Some sugars are capable of reducing copper II ions to copper I ions. This reducing ability is useful in classifying sugars. When the sugar to be tested is added to the Felhing's solution sugars can be oxidized anf felhing's mixture can obtain this electrons.

2. Objectives

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

3. Hypotesis

The hypotesis is to identify which sugars perform felhing reactor's.

4. Material

• Test tube rack
• 10mL pipet
• distilled water
• 5 test tubes
• 5 spatula

• Lactose
• Maltose
• Glucose
• Sucrose
• Starch
• Felhibg's A and B solutions
• HCl

5. Procedure

First of all, we took 5 test tubes from the previous practice and we put 2 mL of Felhin's A and B Feling's solutions and put them to warn up. After 10 minutes we took the test tubes and we observed the results.

6. Observations

We have observed that glucose, maltose, lactose Felhing's reagent changed from blue to orange. And sucurose the mixture with felhing reagent didn't change the same with starch.

7. Conlusions

Monosaccharides  and some disaccharides have reducing power. However polysaccharides like starch isn't reducing sugar.

8. Questions

1. From your observations and the structures of sugars given above, indicate which functional group in the sugar molecules reacts with Felhing's reagent.

The OH from an anomeric C.

2. Compare the results you obtained for the fehling's test of starch and fehling's test of hydrolyzed starch. Explain your results.

If we hydrolize starch, glucose are released and they react with Felhing reagent.

3. Would have you obtained a Felhing's positive test if you had hydrolyzed the sucrose (as you have done with starch)? why?

The sucrose has no free 0H therefore not react with the reagent Felhing, like the starch.

4.  What does " reducing sugars" term mean?

The solutions that react with the reagent Felhing are monosaccharides having a free OH, such as glucose, fructose, sucrose and maltose.