P4. PH

OBJECTIVES

Can see pH and measure different pH substances based on mixing water and lemon. 

MATERIAL 

• Test tubes
• Lemon
• Water
• pH paper detectors
• A beaker. 
• A pipette. 

PROCEDURE 

1. We cut the lemon in half.
2. We squeeze the two pieces  to get lemon juice.
3. Take the pipette for the amounts in ml below. 
4. When we have the tubes with all quantities mixed, add the paper measuring pH to see which number has each mixture. 

Tests tube	H2O (ml)	Lemon (ml)	PH ?
1	1	5
2	2	4
3	3	3
4	4	2

RESULTS

Tests tube	H2O (ml)	Lemon (ml)	PH
1	1	5	3(a tots)
2	2	4
3	3	3
4	4	2

CONCLUSION 

The quantity of water doesn't determinate if the pH is acid (between 1 and 7) or basic (8 and 14), the neutral pH is 7. 
So as we put so much water doesn't mean that the mixture would be more basic. 

QUESTIONS 

1. Which is the dependent variable?  It's the pH.
2. Which is the independent variable? The lemon. 
3. Which is the control? The control is the tub that contains the same quantity of lemon as water. 
4. Which pH do you think that in blood? And in gastric juice? The pH in blood is between 7'35 and 7'45, it has to be neutral, if it was acid we would die; and in the gastric juice is between 0'9 and 1'5, it has to be acid to dissolve different substances.