Science Investigatory Project Question?

Question

Our group in school have decided to do this experiment http://soil.gsfc.nasa.gov/elec/soilelec.... The first time we did it, we were able to make soil stick to the anode (which i think was what was supposed to happen). Unfortunately, when we did it again for a 2nd and 3rd time, nothing happened (we did the exact same procedure). We need to pass our investigatory project this Monday. Do you think our conclusion for the investigatory project should be soil is NOT an electrical system?

Answer 1

Your second, third test should have worked.

Try testing the charge on your electrodes with standard electrical testing devices. Make sure your connections are solid, battery providing a charge, and the polarity has not been switched by accident.

Answer 2

has to be part of the electrical system in most applications...the reason is "electrical grounding" as part of the negative and positive positions of electrical current

Answer 3

Soil has a negative charge in most cases. In soils you get a cation exchange capacity (CEC) determined to show how well the soil will attract and hold cations to the surface of the soil particles. Clay soils have smaller sized particles, thus more total exposed surface and a higher CEC. Sandy soil has a very low  CEC because the soil particle size is much larger so has much less exposed anions (- charged).  Most plant nutrients-Ca, Mg, Na, K, P, etc are cations (+charged) so they are attracted to and attached the - charged soil particles. The important exception to this is Nitrogen ions which are negatively charged and so are not held by the soil. That is why they are easily leached from soils if not taken up by the plant roots, thus causing problems with runoff water and ground water pollution.

As to your experiment, it worked exactly like it should the first time. The anions (clay particles) go to the anode (positive electrode). Why it didn't work the second and third times you tried it? I really can't tell you why, but will give you a recommendation. Try doing experiment over using a completely new soil sample, new wires or electrodes, and maybe even a new battery. Something went wrong for your second and third tries, because soil definitely an electrical system which you demonstrated with your first trial. Good luck with your experiments.