1. Predict how exhaling into water after exercise will change the pH of the water (1 mark).
Provide rationale for your prediction (1 mark). The predicted hydrogen (pH) is expected to decrease and become more acidic once air bubbles are blown into the water. The reaction between the carbon dioxide exhaled and the water molecules (H2O) will produce carbonic acid, which can readily lose hydrogen ions, causing the solution to change the pH becoming more acidic.
2. Provide a tabulated summary of the results for the group for the group from those you recorded in the laboratory manual. What do these results indicate? (4 marks)
Table One: The waters pH before and after exposure to carbon dioxide from external respiration - Class results
Experiment Breathing rate (breaths/minute) Control pH of water Experimental pH of water after blowing bubbles %pH change Class average of % pH change
Average at rest 13 7.13 5.32 29% 24.95%
Minimum value 10 6.30 4.89
Maximum value 14 8.00 5.67
Average after exercise 35 7.67 5.07 38% 34.13%
Minimum value 26 7.38 4.73
Maximum value 40 8.00 5.70 The results indicate that the pH of the water decreased causing the water to become more acidic after bubbles had been blown into the solution. The average percentage of pH change for the class before exercise is 24.95% and after…show more content… A part of external respiration involves the movement of carbon dioxide from the blood into the alveoli of the lungs which is then exhaled through breathing (Farley, A., Hendry, C., Johnstone, C., & McLafferty 2013). The increased carbon dioxide due to exercising exhaled by the individual dissolved in the water molecules forming carbonic acid (H2CO3). The hydrogen ions decreases the pH level causing the water to become more acidic on the pH
