1.4 pH

Introduction
ThepH is a mesure 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 has a pH close to 7, neutral.
The equation of pH:
pH= -log (H+)


Material
-Destilled water
-Milk
-Lemon
-Tomato
-Coffee
-Carbonated beverage
-10% NaOH solution
-10% HCL solution
-NH3 solution
-Soap solution
-Universal indicador paper
-pH-meter
-Acetic acid
-Tongs
-8·100mL beaker
-2 clock glass
-1·250mL beaker
-5 test tube
-10mL pipet
-Test tube rack
-Funnel
-Graduated cylinder


Objectives
-Measure different pH values of organic and inorganic solutions.
-Prove different methods of measuring pH.


Procedure

To measure the pH of different solutions we are going to put the diferrent solutions in small beakers of 250mL.
1.Squeeze the lemon and tomato in two clock glasses.
2.Take a piece of indivstor 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 appropiate 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.


Table of the pH of each of the test tube:

Test	Volume of	Total	Concentration	pH
B	5 + 5	10ml	50	2.2
A1	2.5 + 7.50	10ml	25	2.5
A2	1.3 + 8.7	10ml	15	2.5
A3	1.2 + 8.8	10ml	12	2.6
A	10ml	10ml	1	2.5

Results of the pH with different tubes concentrations:


Our results are wrong bacause we didn't control the volume in each tube.
The pH depends on the proton concentration.
pH= -log (H+)<
We expected that the A test tube (the most concentration) had the lowest pH.


Questions
1.Which of the solutions gave an acid pH?
Lemon, tomato, vinegar, coca.cola, HCl, wine.
2.Which of the solutions was alkaline?
Soop solution, NaOH.
3.Which of the solutions were neutral? Did you expect these results? Explain.
Destilated water and milk. Because it don't have dissolved salts.
4.How does a pH of 3 differ from pH of 4 in terms of H+ concentrations?
In a pH 3 solution there is ten more protons than a solution of pH 4.
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:
 a.Which is the dependent variable? Is the Ph.
 b.Which is the indepedent variable?The lemon juice concentraton.
 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?Test tube B 100% of lemon juice
 e.Write the results and conclusions of your experiment:It is in a table that is up on the page
6.Which pH do you think that gastric juices might have? Why? Do you think that intestinal pH has the same pH? Why?
It's an acid pH, because it have to undo the food. It is getting basic every tame it get away of the stomach.
7.Which pH do you think that blood might have? Why?
7,2 pH
8.What is acid rain? Which are the consequencies in the ecosystems and how its formation pattern? Is rain in Barcelona acid or alkaline?
The acid rain is a toxic rain, which is formed for the emission of gases from factories.
Somethimes there is acid rain but normaly it is alkaline rain.