Water acidification  

Investigative approach to the water acidification experiment 

1. The questioning: "Does the increase of the CO2 rate in the air induce an acidification of the sea water?”

2. The hypothesis: if we increase the rate of CO2 in the air, the PH of the water will decrease which reveals an acidification of the water.

3. Materials:

-  1 elbow tube  

-  2 Erlenmeyer flasks 

-  1 pierced stopper 

-  vinegar 

-  Bicarbonate of soda 

-  PH-meter probe 

-  EXAO software on computer 

4. Experiment: 

-  Mix vinegar and baking soda to obtain a release of

CO2 by chemical reaction

-  The CO2 that is released comes out of the Erlenmeyer flask through the hole in the stopper and enters the water in the second Erlenmeyer flask. 

-  The EXAO software allows us to measure the variation of the acidity of the water in the course of time, by means of the PH-metric probe

5. Results :

The curve of the variation of the PH of the water in the course of time

6. Interpretation of the results: 

We can notice that the PH of the water decreases over time, i.e. when CO2 dissolves in the water.                                                                                                                          We can therefore affirm that an increase in the rate of CO2 in the atmosphere causes an acidification of the sea water which is harmful for Posidonia oceanica.