Question

You decide to do to determine the effect of used cigarette butts on water from Morses Creek, NJ and how it affects the water quality index. In the lab, you set up 3 large tanks of water from Morses Creek for the control group and 3 large tanks for the experimental group.

1. What is the independent variable in this experiment?

2. Name four dependent variables that you should measure.

3. What are three controlled variables?

4. Explain how you should set up the control group tanks. Then explain how you would set up the experimental group tanks.

Answer 1

The independent variable is the one that we are going to study or test (this is the one we are going to isolate)To design an experiment you must first set a hypothesis, in this case Your hypothesis is that the quality of the water is affected by the cigarette butts.

The independent variable is the one that we are going to study, test or manipulate (this is the one we are going to isolate). In this case, it is the quality of the water. The dependent variable is the results of the manipulation of the independent variable (that is, the result of the experiments to be carried out). In this case, to assess the quality of the water, turbidity, content of organic matter, chemical demand of oxygen, demand can be used. oxygen biochemistry, water hardness among many other factors (including coliform bacteria).

3 variables that we can control in this experiment would be the temperature of the water, the amount of water (ie the size of the sample) and add or not the cigarette butts.

For the control groups we need the sample to be tested in this case the water taken directly from the pipe, we also need a negative control that would be pure water, and a positive control that would be water tanks with cigar butts of different origin.