pH

Introduction: 
The pH is a mesure 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. (pH=-log [H+])

Objectives: 
1. Mesure different pH values of organic and inorganic solutions.
2. Prove different methods of measuring pH.

Procedure: 
1- Squeeze the lemon and tomato in two 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 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 result table in your worksheet.

How does concentration affect pH?
6- Prepare the test tube rack with 5 test tubes cleaned with distilled water. Mark the tubes with the labels: A, A1, A2, A3 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 (5ml of distilled water).
9- Take the A1 tube and put 2,5 ml of its lemon juice to tube A2 (7,5ml distilled water).
10- Take the A2 tube and put 1,2 ml of its lemon juice to tube A3 (8,7ml distilled water)
11- Add distilled water to each test tub until it has the same volume as test tube B (10 ml)
12- Calculate the concentration of each test tube with the formula.

Test          Volum of           Total           Concentration           pH
B              5 + 5                    10 ml           0,5                              2,70
A1            2,5+7,2                10 ml           0,25                            2,56
A2            1,2 +8,7               10 ml           0,13                            3,08
A3            1,2+8,8                10 ml           0,12                            3,08
A              10 ml                   10 ml           1                                 2,81

























QUESTIONS:
1. Which of the solutions gave and acid pH? Lemon, tomato, vinagre, coca-cola, HCL and wine.
2. Which of the solutions was alkaline? Na OH, soap solution.
3. Which of the solutions were neutral? Did you expect these results? Explain. Milk,  souy milk. Yes but the milk I though that was an alkaline.
4- How does a pH of 3 differ from PH of 4 in terms of H+ concentrations? HCL, H3 have more H+ than the H4, have 10 more H+.
5-
      a) Which is the dependent variable? Is the Ph
      b) Which is the independent variable? The lemon juice concentration.
      c) Which is the problem that we want to solve? Can the juice lemon concentration variate the          Ph3?
      d) Which is the control of the experiment? Is the B, have 100% lemon juice.
      e) Write the results and conclusions: Independent Variable
6- Which pH do you think that gastric juices might have? why? Do you think that intestinal pH has the same pH? why? Acid, because we need to combine with the food and remove. Fisrt we have basic acid but then change to acid.
7- Which pH do you think that blood might have? Why? Neutral (7,2)
8- What is acid rain? Which are the consequences in the ecosystems and how is its formation pattern? Is rain in Barcelona acid or alkaline? Destruction of forest, brake the rocks. We have acid or alkaline.