P4. pH

Introduction:

• We will measure the pH of: HCl, vinegar, wine, tomato, coffee, distilled water, soap, read and NaOH. We will examine if your pH is acidic, basic or neutral. Also there are pH will look at different concentrations of lemon juice with a pH meter accurate.

Objectives:

1. Measure different pH values of organic and inorganic solutions.
2. Prove different methods of measuring pH.

Hypothesis:

• Each substance has a different pH. 
• The higher the concentration of lemon juice there is in a solution with distilled water, the pH will be more acidic.

Materials:

• Distilled water
• milk
• wine
• lemon
• tomato
• cokke
• carbonated beverage
• 10% NaOH solution
• 10%HCl solution
• NH3 solution
• Soap solution
• Universal indicator paper (strips)
• pH-meter
• Acetic acid
• tongs
• 8 x 100mL Beaker
• 5 test tubes
• Test tube rack
• 10 mL pipet
• Funnel
• Graduated cylinder

Procedure:

• Enter a beaker HCl concentrations, vinegar, wine, tomato, coffee, distilled water, soap, and NaOH read. Looking pH with universal indicator paper pH. We note the acidity of each solution. Look if they have a basic or acidic pH.
• Take 5 test tubes and indicated. The first tube "B", the second "A1", the third "A2" on the four "A3" and the fifth "A". In the tube "B" Enter 10 mL of lemon juice in the tube "A1" Enter 5 mL of lemon juice plus 5 mL of distilled water in the pipe "A2", introducing 2.5 mL of lemon juice over 7.5 mL of distilled water in the pipe "A3" Enter 1.25 mL of lemon juice and 8.75 mL distilled water. In the pipe "A", enter 1.25 mL lemon juice, nothing more. Each test tube will have a total volume of 10 mL, except the tube "A". With an electronic pH meter pH house look dissolution.

Comments:

• To look at the pH of each substance to be used universal pH indicator paper or a electronic pH meter.

Conclusions:

• The test tube with the highest concentration has a higher acidity which has less concentration.

Questions:

1. Which of the solutions gave an acid pH? 

  

   -Solution B

2.- Which of the solutions was alkaline?

Soap, bleach and NaOH.

3.- Which of the solutions were neutral? Did you expect this results? Explain.

Distilled water, because it has the same concentration of H+ and OH, and thats why we expect that water is with a pH neutral.  

                                                                                                  

4.- How does a pH of 3 differ from pH of 4 in terms of H+ concentrations?
10 times large value.

5.- In the second part of the experiment, you have compared the pH of the same product (lemon juice) in different concentrations. In this case explain:

• Which is the dependent variable? The pH.
• Which is the independent variable?The concentration of lemon juice.
• Which is the problem that we want to solve? The problem that we want to solve is equalize the concentrations.
• Which is the control of the experiment? The control is the test B.
• Write the results and conclusions of your experiment: The pH is very similar on the all concentrations, but the normal is that the pH depends of the protons concentrations. 

6.- Which pH do you think that gastric juices might have? Why? Do you think that intestinal pH has the same pH? Why?
They have an acid pH because its used to improve food digestion. I think that all intestinal pH are acid.

7.- Which pH do you think that blood might have? Why?
The blood have an neutral pH, because if is hypotonic the cell bloat, if is an hypertonic the cell crease. The pH causes it to keep the concentration, because we could die.

8.- What is acid rain? Which are the consequences in the ecosystems and how is its formation pattern? Is rain Barcelona acid or alkaline?

The acid rain is a phenomenon, that have a pH levels lower than normal. Is mainly due to the mixture of water with molecular products of sulfur and nitrogen in the combustion incurred, such as nitrous oxide NO2, NO3 nitric oxide or sulfur dioxide SO2 which when combined with the water generated nitrous acid HNO2, HNO3 nitric acid and sulfuric acid H2SO4. 
Acid rain can have harmful effects on plants, animals and buildings. Causes corrosion of metal structures such as bridges or erosions in stone buildings. It also burns the leaves of vegetation and ecosystems it affects mainly vegetables, such as forests, but can also affect lakes and reservoirs acidifying them.
In Barcelona this rain, is alkaline. 

L3. Osmosis

Introduction:

This is a lab on osmosis. Today we will see how a hypertonic medium and a hypotonic environment. We will also see the difference between the concepts isotonic, plasmolysis and turgidity.

Objectives:

1.      Know about the osmosis phenomena.

2.      Understand the process of osmosis in plasmatic membranes.

Hypothesis:

·       

       When you add a lot of salt in a medium, this wrinkle, leaving ana water. When you add a quantitad of distilled water in a medium swell.

Materials:

·         Egg

·         Potato

·         Salt

·         Distilled wáter

·         Acetic acid (or vinegar)

·         Spatula

·         600 mL Beaker

·         3 Clock glass

·         Pen

·         Spoon

·         Knife

Procedure:

·          Cut three pieces of potato peers. By adding a high concentration of salt, the other add distilled water, and the third adds nothing. Let us spend a while to look after a while each sample. 

                      

        Put an egg in a Beaker 600 mL of distilled water. Let us spend a couple of days. Having spent time look egg.

Comments:

·          The potato has been inflated with distilled water, salted potato has wrinkled potato has nothing, as usual. There    is an acute process of osmosis.

Conclusions:

The potato has been inflated with distilled water, salted potato has wrinkled potato has nothing, as usual. There is an acute process of osmosis. 

The egg has been inflated. He suffered a turgidity. 

Questions:

·         Egg experiment:

1.       What is happening  when the shells are soaking of acetic acid?

-          CaCO3 + CH3COOH                 Ca (CH3COO)2 + CO2

2. Write the results of the dimensions and weigh of the egg before and after immersing it in distilled wáter. Write and draw a simple diagram of the water direction.

·         Potato experiment:

3. Explain the results of this experiment:

- The potato has been inflated with distilled water, salted potato has wrinkled potato has nothing, as usual. There is an acute process of osmosis. 

      The egg has been inflated. He suffered a turgidity.

4. Why have we left the first slice without any treatment (salto r distilled water)?

- To compare the results

5. Which are the dependent and independent variables?

-        Dependent: Turgidity of the potato, the presence of water in the cells

-        Independent:salt, distilled water

·         General questions:

6. How can you explain (through osmosis) the ability of plant roots to draw water from the soil?

- The salt concentration of the cells is higher, so water tends to enter.

7. What will it happen if a saltwater fish is placed in a freshwater (low concenttration of salts) aquarium?

- It will die

8. Look the image you have below and explain what is happening to the erythocytes in each situation:

       1) Plasmólisi

       2)Control

       3)Turgid

L2- Minerals salts in organisms.

Introduction:

We will dissolve calcium carbonate scallops and an eggshell. We will also put chicken bones in vinegar, to dissolve organic matter in them.

Objectives:

• Identify mineral salts in organisms.
• Understand the function of inorganic biomolecules in skeletal structures of organisms.

Hypothesis:

• Acetic acid dissolved organic matter and egg shells. It also dissolves M.O. bone, and that means that the bone can bend.

Materials:

1. Some molluscs' shells (mussels, eggs).
2. Dried, cleaned chicken bones.
3. Water.
4. Acetic Acid / Vinaguer.
5. Tongs.
6. 2x200mL Beaker.
7. Clock glass.
8. Distilled water.

Procedure:

• Add a chicken bone in a beaker with 200 mL of vinegar. Like before you put it in the weigh (in our weight 16.6 grams). Once inside, the cover it, and let the acidic vinegar dissolved organic matter. Hopefully a week and see that they afraid to bend.
• Add an egg shell and a shell in a beaker. Adding a large amount of acetic acid and let this digolgui calcium carbonate bearing the egg shell. We leave a couple of days, and once after this time, we realize that the acid has dissolved all the eggshell and shell.

Comments:

• To dissolve the egg shell, we can see bubbles coming out. These bubbles are CO2.

Conclusions:

• The acid dissolves calcium carbonate and organic matter. The dissolved organic matter of the bone, which makes this can be doubled.

Questions:

1. CH3COOH + CaCO3 ----------- CO2(g) + 
2. Releases CO2
3. The bone can be doubled. Because the acid is dissolved organic matter.
4. The rigidity.