L4: PH

    pH

   INTRODUCTION:

The pH is a measure of the acidity or basicity of a solution.Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline . Pure water (distilled water) has a pH close to 7 neutral.
The pH is defined as the following equation:
               

                                                           pH=-log (H+)


For mesuring the pH of a solution at the lab we have different pH indicators:
Universal indicator paper : It't an absorbent paper that has been impregnate with universal indicator. This method consist as a continuous colour change from about pH 2 to pH10.
-pH-meter: is an electronic device used for measuring the exact pH of a solution.It consists of glass electrode connected to an electronic meter that measures and displays de pH reading.

Objective:


1-Measure differents pH values of organic and inorganic solutions.
2- Prove different methods of mesuring pH






 Material:  

-Beaker
-Watch glass
-PH indicator strips
-knife
-1 lemon
-1 tomato
-wine
-milk
-Dissolution of sodium hydroxide
-Vinegar (acetic acid)
-Hydrochloric acid 10%
-ammonia
-bleach
-distilled water
-dissolution soapy




Procedure :

To measure the pH of different solutions  we arebgoing to put the different solutions small beakers of 250ml

Squeeze the lemon and tomato in two clock glasses. Take a piece of indicator paper and place one end of it into the solution . Leave for at least 20 seconts.Remove the indicator paper and compare its colour with  the appropriate colour chart. Repeat points one to two with as many others solutions as you are provided with.Record your results in a resuls table in your worksheet.
The consentrer of pH

Prepare a test tub rack with five test tubes cleaned with distiller water.Mark the tube with the labels:A, A1,A2,A3 and B
Add 10ml of lemon juice to tubes A and B
Take the A tube and put 5ml of ist lemon juice to test tube A1
Tke the A1 tube and put 2,5 ml of its lemon juice to tube A2
Take the A2 tube and put 1,2ml of its lemon juice to tubeA3
Add distilled water to each test tube until in has the same volume as test tube B 10ml
Calculate the concentration of each test tube with the formula you have below:

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

TEST	VOLUME OF	TOTAL	CONCENTRATION	pH
B	10	10ml	100%	2,95
A1	5	10ml	25%	3
A2	2,5	10ml	12,5%	3,05
A3
A	10	10ml	50%	3

Observaccions:

Enter peaquimetres to see solutions and the degree of accidesa they had, then the lemon we had another experiment fen differents consentrecions acid and distilled water with lemon .But the result was different between the degree of co accidesa gave us.





Questions 

Which of the solutions gave an acid pH? HCL ,Vinager,Tomato,Coffe,Wine,Milk
Which of the solutions was alkaline? Soap,NAOH,Bleach
Which of the solutions were neutral?Did you expect these results? Explain.
Destiled  wotter , because we noticed a small amount of salt and.
How does a pH of 3 different from pH of 4 in terms of H concentrations?  Que el tres te  deu vegades mes protons que la quatre
In the second part of the experiments ,have you have compared the pH of the same product (lemon juice) in different concentrations . In this case explain.
concentration varies lemon juice distilled water possavem that was more acidic or neutral

a-Which is the dependent variable? is pH
b-Which is the independent variable? Dissolution is that we put distilled water
c-Which is the problem that we want to solve?distilled water so that the lemon juice makes it more neutral
d- Which is the control of the experiment?
e-Write the results and conclusions of your experiment:
Els resultats de l'experiment no son correctes el peaquimetre es va descalibrar

Which pH do you think that gastric juice might have?Why?Do you thinks in intestinal pH has the same pH?Why? Tenim en el nostre estomag acid gastric que te un pH de 12-13 tenim acid cloridric que ens desfa els aliments i tenim una pared a lestomag perque aquets sucs gatrics no surtin ja que podrien provocar molt de dolor.

Which pH do you think that blood minght have?Why? Es de 7,2 intentaser lo mes neutre possible perque no pogui tornar la sang que porta l'aigua i altres conponens de vital inportancia en acids o basics
What is acid rain? Whichare the consequencies in the ecosystems and how is its formation pattern ?In rain Barcelona acid or alkaline ? Es tota la pluja que presenta un pH inferior al del normal, es perjudicia pel creixement de les plantes i contribueix al deteriorament del medi. Es produeix per que en la humitat de l'aire  hi ha sofre nitrogen que produeixen les fabriques.