Science Buddies: "Ask an Expert"

Help! I don't think we are doing this right. The experiment is supposed to be complete by 10/31. I performed my project to test electrolytes in Gatorade, tap water, distilled water, coconut water, and powerade. I got almost the same result for all. That doesn't seem right. My mom and dad looked at it, and we can't figure out what we are doing wrong. For example the results were .43, .44, .46 for distilled water, .47, .46, .44 on Gatorade on the three tests. I thought distilled water would be zero. What are we doing wrong? Is this a correct reading? Would the math be to divide by 1000 and then by 9. So, for a result of .43, the conductance would be .00047777?

barnold - You are correct in that the distilled water should be virtually 'zero'. The most common problem with this experiment is the multimeter setup. Here are things to look for.

1) Are the test leads in the proper sockets? The black lead should be in the socket market 'COM'. The red lead in the 'VΩmADC' socket (or similar legend). Do not use the '10ADC' socket
2) Set your multimeter to 200mADC range to start.
3) Is your battery near fresh. If the battery is weak, the sports drink of other highly ionized liquid will heavily discharge the battery causing false readings.
4) Is your sensor constructed of non-insulated copper wire. Even copper magnet wire can look 'bare' but may have a transparent varnish coating.
5) Check your wiring setup carefully.
6) Is your multimeter functioning in the DC current ranges? Often a protective fuse inside the meter may be blown.

Check back with us if you still have problems.

Rick Marz