SIXTH EXPERIMENT: Saponification.

• Materials:

1. 900 mL beaker.
2. Spoon.
3. Clock Glass.
4. Bascule.
5. Rod.
6. 32 g NaOH.
7. 90 mL H2O.
8. 270 mL recycled oil.

• Procedure:

We take 32 grams of NaOH in 90 mL water and mix to dissolve you, then let throwing the oil slowly while saponification happens.

• Results:

CH3-(CH2)7-CH=CH-(CH2)7-COOH + NaOH --->  CH3-(CH2)7-CH=CH-(CH2)7-COONa + H2O

FIFTH EXPERIMENT: Lipids Properties

• Introduction:

These compounds are characterized as natural substances taht do not mix with water but dissolve in organic solvents.

Lipids are made in general of a long chains of hydrocarbons with relatively little oxygen.As a result of this, they tend to be non-polar, meaning they do not dissolve in polar solvents such as water.

• Materials:

1. Test tube rack.
2. 250ml beaker.
3. Water.
4. 6 test tube.
5. Cellulose paper.
6. Dropper.
7. Scissors.
8. Glass rod.
9. Olive oil.
10. Soap (detergent)
11. Milk with different fat content: Full-cream, semi-skimmed and skimmed milk.
12. Petroleum ether.
13. Ethanol.
14. Sudan III.

• Procedure:

Solubility of some lipids:

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

 

 

• Results:

The oil and ethanol don't dissol in water and ether can dissol in water.

Lipids identification:

      Translucent Mark:

1. Cut two pieces (10x10cm) of cellulose paper.
2. Put 1 drop of water in the first squared piece. You will see a transluced spot. Wait for a while and observe what is happening.
3. Put 1 Drop of olive oil in the second suqred piece of cellulose papaer. You will see a transluced spot. Wait for while and observe what is happening. Has the spot dissapered? Why?

• Results:

The oil is transluced because doesn't evaporate, water can evaporate.

Sudann III dye: Be careful Sudan red cxan stain clothes!

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

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

• Results:

The proof of Sudan III doesn't work possibly because the solution was too diluted.

Permament emulsion:

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

• Results:

The oil is translucent because it doesn't evaporate, however the water if it evaporates, leaving different stains.

• Questions:

1. From your observation, wich compunds can dissolev lipids? Ether
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, the oil non-polar.
3. Why is liquid the olive oil at room temperature? And why not the lard? Because is the faty acid insaturated. The lard is a faty acid saturated.
4. Why does the lipid leave a translucent spot on paper? Because the lipid does not evaporate.
5. Wich type of milk contains more lipids? Why? Milk full-cream, because they take away the semi-skimmed milk fats.
6. Did the oil and water mix when you added the soap?No, but a monolayer and a micelles separated oil from water formed.
7. What did the soap do to the fat? Separated in micelles.
8. Can you think about process and locations were compounds like the soap would be important to an animal? Acids biliars.



FOURTH EXPERIMENT: Saccharides Properties

• Introduction:

Saccharides are organic molecules consisting of C, H and O atoms. Usually the empirical formula is C_nH_2nO_n . Are divided into three groups:

-Monosaccharides: formed by a linear carbon chain, are the building blocks of oligo and polysaccharides.
-Oligosaccharides: small polymer containing between 2 and 10 monosaccharides.
-Ploysaccharides: big polymers with more than 10 monosaccharides.
Saccharides yield 4,2 Kcal/gr.

• Materials:

1. Test tube rack.
2. 10 ml pipet.
3. Water.
4. 5 test tubes.
5. 1 dropper.
6. 1 Spatula.
7. Lactose.
8. Maltose.
9. Glucose.
10. Sucrose.
11. Starch.
12. Lugol's iodine.
13. Distilled Water.

• Procedure:

Complete the properties' table that you have below from the 5 saccharides you have at the lab:

	Glucose (G)	Maltose (M)	Sucrose (SU)	Lactose (L)	Starch (S)
Flavour (sweet/no sweet)	sweet	sweet	Very sweet	No sweet	No sweet
Cystalline from	crystalline	no cystalline	cystalline	no crystalline	no crystalline
Colour (white/cream)	white	white	white	white	cream
Solubility (soluble/insoluble)	soluble	soluble	soluble	soluble	Insoluble
Lugol's iodine (+/-)	-	-	-	-	+

                                            

1.      In the first part of the experiment we are going to test some physical propierties of the saccharides you have in the lab: flavour, crystal structure and colour. How?

a)      Flavour: put  a small amount of each saccharide in your han and taste it! Is it sweet or not?

b)      Crystals: Observe a small amount of each  saccharide on a clock glass under magnification.

c)      Colour: White, trasparent or creamy.

To test solubility:

2.      Clean and  dry 5 test tubes and label them  "G, M, L, SU, S".

3.      Put 5ml of water in each test tube.

4.      With the aid of a spatula, put a small amount of eavh saccharide inside the labelled test tube and test tube if they are soluble or insoluble.

5.      Observe if each saccharide forms a mixture called dissolution or a colloidal suspension.

Lugol's iodine Test:

6.      Finally, add 2 drops of Lugol's iodine to each test  tube and test if the reaction is positive or negative. Lugol's is a solutions of elemental iodine (I) and potassium iodine (KI) in waterr that is use to test a saccharide. The reaction is positive when iodine reacts by turning from yellow to a purple, dark-blue/black colour.

Finally we are going to test if some foods contain starch. Try with potato!

1. Add 2 or 3 drops of lugol's solution to one piece of potato and observe what is happening.

• Questions:

1. Write the empirical formula of each saccharide that you have use. Show structures of the five saccharides. Classify each in one group: mono, oligo or polysaccharide.
   

   Glucose (mono): C₆H₁₂O₆

   Maltose (disaccharide): C₁₂H₂₂O₁₁ · H₂O

   Sucrose (disaccharide): C₁₂H₂₂O₁₁ · H₂O

   Lactose (disaccharide): C₁₂H₂₂O₁₁ · H₂O

   Starch (polysaccharide): (C₆H₁₀O₅)_n
2. Which of the monosaccharides are aldoses and wich ketoses? Aldoses: glucose, maltose, lactose, starch. Ketoses: sucrose.
3. Which bond links monosaccharides? Oglicocidic.
4. Which saccharide/s is/are insoluble? Is this property related to the structure of the molecule? Glucose, Maltose and Sucrose. Polysaccharides.
5. Which saccharide/s is/are insoluble? Is this property related to the structure of the molecule? Starch, high molecular density.
6. Wich saccharide has reacted with Lugol's iodine solution? Starch.
7. Which kind of food contains starch? Flour, cereal, pasta, rice, legums, etc.
8. Caculate the energy that comes from the saccharides. 23gr saccharides · 4,2 Kcal/gr = 96,6 Kcal.

   
   

Fheling's test: reducing sugar.

• Introduction:

Fehling's solution is a chemical test used to different 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 A: is a blue aqueous solution of copper (II) sulphate.
Fehling's B: clear and colourless solution of potassium sodium tartrate and sodium hydroxide.

• Procedure:

In this experiment you will first determine with sugars give a positive test Fehling's reagent and then, by testing the reaction of some organic molecules containing onlya single functional group, you should be able to deduce which functional group of sugar is reacting with Fehling's reagent:

1. Take 5 test tubes and label: G, M, S, L, ST.
2. Put 2 mL of distilled water inside each tuve.
3. With different spatulas put a small amount of each sugar. Dissolve the sugar.
4. Add 2mL of Fehling's A solution and then Fehling's B.
5. Place each test-tuve in a boiling water bath (250mLbeaker on a hotplate stirrer).
6. Observe what is happening.

Starch Hydrolysis:
Hydrolysis is the reaction of a compound with water. As you know, starch is a polymer, consisting of many units of α-D-glucose covalently linked together.

1. Place 2mL of 1% starch in a test tuve and add 0.5mL of 3M HCl. Mix and place this mixture in a boiling water bath for 10 minutes.
2. After 10 minutes, remove the tuve from the water bath and let it cool. Neutralize this solution with 1M NaOH and mix well.
3. Transfer 8-10 drops of this solution to a small test tuve.
4. Add 1mL of Fehling's A solution and 1mL of Fehling's B.
5. Heat for a few minutes in a boiling water bath.
6. Record your observations. Compare the results of this test with your results for unhydrolyzed starch in the step 1 of this experiment.
7. You can test the absence of starch with iodine solution too!!

•  Questions:

1. From your observations and the structures of the sguras given above, indicate wich functional group in the sugar molecules reacts with Fehling's reagent. Glucose, Fructose, Maltose, Lactose
2.  Compare the results you obtained for the Fehling's test of the starch and Fehling's test hidrolyzed starch. Explain results. The starch react and becomes blue, because it react with lugol's iodine.
3. Would have you obyined a Fehling's positive test if you had hydrolyzed the sucrose (as you have done with starch9? Why? The sucrose has no free OH.
4. What does "reducing suars" term mean? Are reacting positively reduces teh Fehling's test. Because it has a fre OH.

THIRD EXPERIMENT: pH

• Introduction:

The pH is a mesure of the acidity or basicity of a solution. solutions with a pH less than 7 are basic or alkaline. pure water (distilled water) has a pH close to 7, neutral. 

pH=-log(H⁺)

• Materials:

1. Distilled water.
2. Milk.
3. Wine.
4. Lemon.
5. Tomato.
6. Coffe.
7. Carbonated beverage.
8. 10% NaOH solution.
9. 10% HCl solution.
10. NH₃ solution.
11. Soap solution.
12. Universal indicator paper (trips).
13. pH-meter.
14. Acetic Acid.
15. Tongs.
16. 8 x 100 ml Bgeakers.
17. 2 Clock glass.
18. 1 x 250 Beaker.
19. 5 test tube.
20. Test tube rack.
21. 10 ml Pipet.
22. Funnel.
23. Graduated Cylinder.
     

• Procedure.

To mesure the pH of different solutions we are going to put the different solutions in small beakers of 250ml.

1. Squeeze the lemon and tomato in tho clock glasses.
2. Take a piece of indicator paper and place one end of it into the solution. Leave for at least 20 seconds.
3. Remove the indicator paper and compare its a colour with the appropriate colour chart.
4. Repeat points 1 to 2 with as many others solutions as you are provided with.
5. Record your results in a results table in your worksheet.

How does concentration affect pH?

Squeeze the rest of the lemon inside a beaker and filter the solution with a funnel and cellulose paper.

     6. Prepare a test tub rack with 5 test tubes cleaned with distilled water. Mark the tubes with the labels: A, A1, A2 and B.

     7. Add 10 ml of lemon juice to tubes A and B.

     8. Take the A tube and put 5ml of its lemon juice to the test tube A1.

     9. Take the A1 tube and put 2,5ml of its lemon juice to tube A2.

     10. Take the A2 tube and put 1.2 ml of its lemon juice tu tube A3.

     11. Add distilled water to each test tube until it has the same volume as test tube B (10ml).

     12. Calculate tehe concentration of each test tube with the formula you have below:

                          Concentration(%)= (Volume of juice/ Total Volume) x 100

      13. Find the pH of each of the test tube and record the information in the table:

  

Test	Volume of	Total	Concentration	pH
B	10 ml	10 ml	100%	3,38
A	5ml	10 ml	50%	3,35
A1	2,5 ml	10 ml	25%	3,37
A2	1,25 ml	10ml	12,5%	3,33

14. Graoh your results on graph paper for the pH of different tubes (concentrations). Be sure to include the following: Title, clearly labeled X and Y axis, use a ruler and colored. To publish it in your blog, tou can do it in Excel or take a picture with you mobile device.

 

 The results should have been others but the pH meter is unbalanced.

•  Results or Observations:

When we placed the strips in the different compounds could be differentiated differents colors therein.

And in the experiment of lemon juice having different concentrations of juice, the pH-meter pH told different numbers.

• Conclusions:

Placing the strips in the various compounds note that in each a different color product devido their acidity, neutrality and basicity out.

• Questions:

1. Which of the solutions gave an acid pH? HCl, vinegar, wine, tomato, cofee, milk.
2. Which of the solutions was alkaline? Soap, Bleach, NaOH:
3. Which of the solutions Were neutral? Did you expect these results? Explain. Distilled water. Yes, because it has no minerals.
4. How does a pH of 3 differ from pH of 4 in terms of H⁺ concentrations? The value is ten times.
5. In the second part of the experiment, you have compared the pH of the same product (lemon juice) in teh different concentrations. In this case explain:

                 a. Which is the dependent variable? The pH.

                  b. Which is the independent variable? The lemon concentration.

                  c. Which is the problem that we want solve?Know which is the pH at different concentrations.

                  d. Which is the control of the experiment? The tube B.

     6. Which pH do you think that gastric juice might have?Why? Do you think that intestinal pH has the same pH? Why? An acid pH, because gastric juice has compond for hydrochloric acid. No, because it has to unpack the food.

     7. Which pH do you think that blood might have? Why? A neutral pH, because this crossing the body and can not be acid.

     8. What is acid rain? Which are the consequence in the ecosystems and how is its formation pattern? Is rain In Bracelona aid or alkaline? Acid rain is when pollution affects the composition of the clouds and the water gets more acidic than normal.It can affect the ecosystem, killing plants and trees. The Barcelona is acid rain as it is a central city where mucho The Barcelona is acid rain as it is a central city where much CO₂ is emitted.