Jamie+and+Alex


 * __Measuring the conductivity of various chemicals dissolved in water in different amounts__**


 * Aim**

To find the conductivity of a solution of water and various chemicals in different amounts. The chemicals are: NaCl, C6H12O6, Fe, Cu, HCl, Al, and Fe2O3. Also, there will be a control of plain water. The first amount used will be 1g / 100 g H2O. Depending on the results, different amounts will be used.

Independent variable: The different chemicals and their concentrations Dependent variable: The conductivity of the solution

A fish company wants to find the best way to electrocute fish in a tank. They want to use the minimum of electricity no matter the cost, so they are willing to mix chemicals into the tank to do so. They have hired us to find the chemical that at the right concentration will cause the fish to die with a minimum of current.


 * Background**

//General background information about conductivity// http://lakeaccess.org/russ/conductivity.htm http://www.jp.horiba.com/story_e/conductivity/index.htm

A fish company wants to find the best way to electrocute fish in a tank. They want to use the minimum of electricity no matter the cost, so they are willing to mix chemicals into the tank to do so. They have hired us to find the chemical that at the right concentration will cause the fish to die with a minimum of current.

Sending electrical currents will generally kill living organisms. This has been proven on electric chairs and other cases. Thus sending electrical current through a tank should kill the fish inside.

There must be a minimum electrical current to kill the fish. If the current is not strong enough, the fish will not die.

All materials have resistance to electricity; that is, when electricity flows through the material, the voltage lessens. In order to use the minimum amount of electricity, the resistance must be reduced as much as possible.

The opposite of resistance is conductivity. The more conductive something is, the less resistance it has. Thus to lower resistance we should maximize conductivity. This will allow the fish to be electrocuted with the minimum amount of electricity.


 * Materials/Procedure**

Needed materials: Beakers holding up to 150 grams of solution; distilled water; at a minimum of 50 g of each of the following chemicals: NaCl, C6H12O6, Fe, Cu, HCl, Al, and Fe2O3; and conductivity testers. Repeat the following for each chemical. 1) Pour 100 g of water at a constant temperature into the beaker. 2) Put the 1g of chemical into the beaker. 3) Let the chemical settle. 4) Use the conductivity tester to measure the conductivity of the solution; record. 5) Repeat steps 3 and 4 for different amounts of chemicals as deemed necessary.


 * Results**
 * Chemical || Concentration (g / 100 g H2O) || Conductivity (µS/cm) || Special notes ||
 * None || - || 200 || Control ||
 * NaCl || 1 || 4058 || Possibility of killing various species of fishes before shock ||
 * || 5 || 4093 ||  ||
 * || 10 || 4107 ||  ||
 * Fe || 1 || 242 || Fe did not dissolve ||
 * || 5 || 312 ||  ||
 * Cu || 1 || 82 || Cu did not dissolve ||
 * || 5 || 74 ||  ||
 * Al || 1 || 100 || Al only kind of dissolved ||
 * || 5 || 95 ||  ||
 * Fe2O3 || 1 || 250 || Fe2O3 only kind of dissolved ||
 * || 5 || 1436 ||  ||
 * C6H12O6 || 1 || 82 ||  ||
 * || 5 || 76 ||  ||
 * HCl || 0.2 || 4067 || Might kill the fish before the ||
 * || 0.5 || 4058 || electricity does ||
 * || 1 || 4089 ||  ||
 * || 5 || 3824 ||  ||

This information is largely irrelevant. These chemicals did not actually dissolve, so they would not affect the conductivity of the water in a the actual situation. It appears that the changing conductivities occurred because of the chemical powder being on the conductivity probe itself, and not because of any actual change in the water.

Unfortunately, there is a paucity of of nonionic chemicals in this experiment. The only nonionic chemicals is glucose. Generalizing, nonionic compounds in general cause more resistance in the water and thus less conductivity. This idea is further strengthened by the fact that as more sugar is added, the conductivity drops. It would be better to test other nonionic chemicals to confirm this hypothesis.

The two ionic chemicals that were tested, NaCl and HCl both had extremely high conductivity. It is also possible that the effect is due to the chlorine, but it is rather doubtful that a single certain chemical will cause conductivity to go up. This could be tested by measuring conductivities of other ionic chemicals without chlorine. It appears that either salt or hydrochloric acid should be used to kill the fish. However, it is preferable to use salt. Hydrochloric acid might kill the fish before the electrocution does. Salt may kill freshwater fish, but these fish would probably survive long enough to be electrocuted and killed.

It appears that the more salt there is, the more conductive the water is. Thus, it would be best to add as much salt as possible, up to the point of saturation.

However, it may be better to test other ionic compounds first and with a more accurate conductivity probe before making the final decision.