An independent variable is the factor that is changed in order to test the hypothesis. The dependent variable was the pH of the water. The dependent variable of an experiment is the variable that is measured. As a control I used water that did not interact with any soil. A control is a trial in the experiment where the independent variable is not applied in order to know why change occurs. A constant is something that is kept the same between trials so that it is sure that it is the independent variable that makes the change. Some constants used in this experiment were keeping the quantity of the soil the same in each trial, having each sample combined for the same amount of time (pp: elaborate), and using water with the same starting pH each …show more content…
My control (the cup without soil) did not change from its original pH of 7, while the water in the rest of my samples did. This proves that it was indeed the soil that caused the change in pH. This data therefore supports my hypothesis that if water interacted with soil, then the pH of the water would change. Each sample, other than the control, caused the water to go to a lower or more acidic pH. This is likely because the soil samples had a higher concentration of hydrogen ions than the water. These probably spread from the soil to the water, lowering the