Activity 9: Flocculation - pH

Activity 9: Secondary treatment - flocculation - pH

Team: Elena Montiel, Marina García i Àlvaro Rivas

Date: 27/11/18

1.   Aim of the study

For this project we had to check the ph of the same substance but different amount of quantity, on this case with water and drops of lemon juice, putting this two substances together we saw that the amount of ph of it can change depending on the quantity of each substance. The more water it had, more ph and more stable it was, and the more lemon juice it had more acid the substance was, we can see this thanks to the ”ph indicator”, which changed the color of the paper depending on the ph of the measured substance.

2.   Materials

-       Two smallest beakers

-       Test tube (4)

-       Pipet

-       Dropper

-       Lemon (1)

-       Distilled water

-       Indicator of Ph

3.   Methodology

So we grabbed four test tubes and put in 2 ml of water in each, except one of them, then we putted different amount of drops of lemon juice on each test tube (the first one with two, then 4 and 6, the final one with 2 ml of this substance), then we mixed the substance and then we measured the ph of each, after observe it, we saw that all of them were acids, so we tried to turn them into most basic substances, making them more stable, to do that we had to more water in each test tube, to compensate  the amount of drops of lemon juice and water.

4.   Results and discussion

The results that can we extract of this experiment is that the water has remained of a yellowish color and the lemon more thrown to orange. Then we throw 1ml more of water in each test tube and the indicator of Ph show us a lighter color.

5.   Conclusions

The goal of this experiment was to find and see, which number of pH had each test tube with different quantities (drops) of lemon we've put. Later we’ve calculated the amount, in ml, of lemon and the concentration with the program excel. Finally we did a graphic that explains that depending on the amount of drops of lemon you put the pH can be higher and changes the colour.

You can also suggest improvements for future experiments.

6.   References

There’s any references only the explanation of the teacher.

Questions:

1. Which is the dependent variable? Which is the independent one?

In my opinion the two substances are dependent because if you want to decrease the ph, make the substance more acid, you have to put more lemon juice on it, and if you want to increase the ph you would have to put more water to make it more basic and stable.

2. Why should we consider two control test tubes? Which ones?

To compare the two different situations, the one with more lemon juice and the one with more water in it. Doing this we can observe the different ph in the two different solutions at the two test tubes. In this way is way easily than doing all at once, if you do it in two or more test tubes you can compare them at the same time and same conditions, so it’s more reliable.

3. Which is the pH in blood? And in gastric juice?

Blood pH measures the acidity of the blood, and normal levels are anywhere between 7.35 and 7.45, there are considered normal. Anywhere above or below that can lead to serious health problems. The pH of the gastric juice varies, from 1-2 up to 4-5, considering different situations, like depending on after the digestion or the meal type (proteins..).