Electrolyte Challenge

deleted-88051 · Post by **deleted-88051** » Mon Dec 12, 2011 2:44 pm

Hi, I'm doing the electrolyte challenge using OJ, lemonade flavored Gatorade, distiller water, and tap water. I've looked at other results and they don't look anything like mine. My results from my multimeter (which is a Innova 3300) were: distiller water 0.00; tap water 0.00; Gatorade 0.02; OJ 0.05. I haven't done the conductance formula yet. When I measured my electrolytes. I tested it under the DC10A setting. What does the 10A mean? Is it already in amps or do I have to convert it to amps? Also for the conductance formula (conductance=current/voltage), what would the voltage be if I was using a 9v battery? Lastly, is my data specific enough because others got it down to 0.025 and stuff. Please help! My data is due by 12/22/11.

deleted-88051 · Post by **deleted-88051** » Mon Dec 12, 2011 2:47 pm

I just posted this in another topic under Electrolytes, but I didn't know if I was supposed to make a new topic (sorry new to this

). Hi, I'm doing the electrolyte challenge using OJ, lemonade flavored Gatorade, distiller water, and tap water. I've looked at other results and they don't look anything like mine. My results from my multimeter (which is a Innova 3300) were: distiller water 0.00; tap water 0.00; Gatorade 0.02; OJ 0.05. I haven't done the conductance formula yet. When I measured my electrolytes. I tested it under the DC10A setting. What does the 10A mean? Is it already in amps or do I have to convert it to amps? Also for the conductance formula (conductance=current/voltage), what would the voltage be if I was using a 9v battery? Lastly, is my data specific enough because others got it down to 0.025 and stuff. Please help! My data is due by 12/22/11.

rmarz · Post by **rmarz** » Mon Dec 12, 2011 7:46 pm

rubberducky1276 - In this experiment will measure current values from zero to just a few microamps for distilled water, and upwards of 30-100 milliamps in some of the drinks being tested. Your use of the 10 Amp range is inconsistent with the levels of current being measured. I assume you have used the special 10 Amp socket for your black probe. Change your black (negative) probe to the COM (center socket on this multimeter) and leave the red (positive) probe in the V Ω mA socket. Then set your range to 200 milliamps for the measurements. It's possible that the distilled water may show a zero reading on this scale, so you can change your range to a much lower level. Because it is a digital multimeter, the reading you get will be in whole units of the scale setting. In the 200 milliamp range, a reading of 20.9 is 20.9 milliamps.

To do your conductivity calculations, assuming a reasonably fresh 9 volt battery: on the lower current ranges you can probably assume that the full 9 volts for your calculation. If you are drawing something like 100 milliamps, there might be a slight reduction in voltage due to internal resistance of the battery at the higher current drain. To be very precise, if you have access to a second multimeter, you could monitor the actual DC voltage across the electrodes that are inserted into the electrolyte. Use that value in your conductance calculation.

Rick Marz

deleted-71882 · Post by **deleted-71882** » Tue Dec 13, 2011 10:57 am

See answer in duplicate posting. https://www.sciencebuddies.org/science- ... =26&t=8611

WW

deleted-88051 · Post by **deleted-88051** » Sat Dec 17, 2011 9:18 am

wendellwiggins wrote:See answer in duplicate posting. https://www.sciencebuddies.org/science- ... =26&t=8611

WW

I kept clicking on the link but nothing happened

deleted-88051 · Post by **deleted-88051** » Sat Dec 17, 2011 9:24 am

Rick Marz,
I changed my red probe to the V Ω mA socket and then black probe I left in COM. I set my range to the 200 milliamps setting under DCA but nothing happened for any of the fluids. Then I changed it to 20 then the lowest, but still, nothing happened. I redid my conductance sensor and replaced the 9v battery with a new one. I don't know why I'm not getting any results. The wires aren't touching and everything is connected. Am I supposed to measure the electrolytes under DCA or DCV? I'm really confused and my teacher doesn't know what to do. Please help!

rmarz · Post by **rmarz** » Sat Dec 17, 2011 11:14 am

rubberducky1276 - If all your connections are correct, and your battery is new, you should definitely get some reading on the 200 ma DCA scale with a sports drink or orange juice. If you have access to a 1,000 ohm resistor, connect it to your two electrodes in place of the electrolyte. You should read about 9 ma. Is your sensor using bare copper wire? Do other functions on your multimeter work? Can you read 9 volts DC on the 20 volt VDC scale. If you have the 1,000 ohm resistor, does the ohmmeter read the proper value? These tests are just trying to resolve that your meter is functioning. The circuit is very simple. The battery is connected in series with the multimeter and is in series with the electrolyte under test.

Rick Marz

deleted-88051 · Post by **deleted-88051** » Sat Dec 17, 2011 12:10 pm

I realized that my fuse on multimeter broke. After retesting with a new fuse, I got:
Distilled Water-0.0
Tap Water-2.1
Gatorade-22.1
Orange Juice-48.2
These results still don't seem right though. I don't know. I am using bare copper wire. I measured it under 200m on DCA. I haven't done my conductance calculations yet too. Sorry for the trouble.

rmarz · Post by **rmarz** » Sat Dec 17, 2011 5:00 pm

rubberducky1276 - Congratulations! These measurements seem to be in the range I would expect in this experiment. I believe you can do your conductance calculations with these results.

Rick Marz

DJ Cha-Z · Post by **DJ Cha-Z** » Wed Dec 21, 2011 6:09 pm

For my science fair experiment, I am doing the Electrolyte Challenge with a 9volt battery - measuring milliamps and calculating conductance using the formula G=I/V where G is siemens, I is amps and V is volts. I am testing Gatorade, Powerade, Propel, Apple Juice, Grape Juice, and Orange Juice, with three trials for each liquid. For Gatorade, I had an average of 0.0196 milliamps (.0000196 amps), and a conductance of 0.00000217 siemens. For Powerade, I had an average of 0.0203 milliamps, and a conductance of 0.0000018922 siemens. For Propel, I had an average of 0.013 milliamps, and a conductance of 0.0000014 siemens. For Apple Juice, I had an average of 0.011 milliamps, and a conductance of 0.0000012 siemens. For Grape Juice, I had an average of 0.0133 milliamps, and a conductance of 0.00000114 siemens. For Orange Juice, I had an average of 0.025 milliamps, and a conductance of 0.00000227 siemens.
Questions:
1) Are these results reasonable for this experiment?
2) Should I report the conductance in micro-siemans i.e. 2.17 micro-siemens vs. 0.00000217 siemens?

rmarz · Post by **rmarz** » Wed Dec 21, 2011 6:57 pm

DJ Cha-Z - Your readings seem to be 3 orders of magnitude off. I think this is a problem of which scale on the multimeter you are using and possibly your interpretation of the values. For this experiment the meter is usually set to the 200 milliamps scale. Readings on the digital readout are in milliamps. For distilled or tap water, a more sensitive range like 20 microamps might be suitable. Otherwise the kinds of values you are seeing look appropriate. I would a suggest that your reading for Gatorade might be 19.6 milliamps, not 0.0196 milliamps. These will obviously significantly impact your conductance calculations.

Rick Marz

DJ Cha-Z · Post by **DJ Cha-Z** » Wed Dec 21, 2011 10:23 pm

If we do the calculation using 19.6 milliamps or 0.0196 amps divided by 9 volts equals 0.00217 siemens. Does this look right, and if so, should we report that as 0.00217 siemens or 2.17mS (milli-siemens)? Which is considered the proper notation?

rmarz · Post by **rmarz** » Thu Dec 22, 2011 1:26 am

DJ Cha-Z - I think it is important to trace your steps to understand the readings you were getting, and the correct setup of the multimeter. Once you have verified that you have the correct readings then finalize your conductance calculations. For ease in understanding, I think it correct that you use whole numbers in expressing your results, thus the form of 2.17 millisiemens would be appropriate.

Rick Marz

DJ Cha-Z · Post by **DJ Cha-Z** » Tue Dec 27, 2011 10:22 am

My numbers were way off because I realized that my fuse on my multimeter broke. After retesting with a new fuse, I got the following results:

Gatorade-1.61 millisiemens
Powerade-0.73 millisiemens
Propel-0.76 millisiemens
Apple Juice-1.16 millisiemens
Grape Juice-1.31 millisiemens
Orange Juice-2.06 millisiemens

Are these results accurate?

deleted-71882 · Post by **deleted-71882** » Tue Dec 27, 2011 1:26 pm

DJ Cha-Z,

Your results seem reasonable now. Be sure to check pure water to be sure you get a low reading with it.

WW

saylespk · Post by **saylespk** » Tue Dec 27, 2011 4:30 pm

The goal of this project was to determine, which of these 3 sports drinks (Vitamin Water, PowerAde, and Gatorade) supplied the most electrolytes versus chocolate milk. For this experiment I used a multi-meter that was used for measuring electrolytes in each drink. The control was distilled water. I performed three controlled tests on each solution. Unfortunately, I'm getting the same reading for ALL: 9.6

1) Cut two pieces of copper wire (6 inches long).
2) Use the princess frog (rubber) as the sensor.
3) Wrapped one piece of copper wire several times around the one of the leg (like you are winding a yo-yo). Leave about 2 inches unwound
4) Did step 3 again on the other side of the leg and ensured the two pieces of copper wire don't touch.
5) Connected the battery to the battery clip.
6) Took the positive end of the multi-meter and connect it to the positive terminal of the battery with an alligator clip.
7) Took one of the copper wires (sensor -princess frog and wrapped with copper wire), attach an alligator clip to it and the other end of the alligator clip and connected to the negative terminal of the battery.

Took the negative end of the multi-meter and connect it to the sensor (other princess frog) with an alligator clip.
9) The sensor (princess frog) was submersed in the drink sample and the results were recorded for each trial.

And as I stated, still getting a reading of all drinks of 9.6.

PLEASE HELP!!!

rmarz · Post by **rmarz** » Sat Dec 31, 2011 9:26 am

saylespk - This question was posted in two different locations. I responded to one, but in case you didn't see it, here was my input. RM

After diagramming your connections, they all seem to be correct. Usually this experiment uses a sensor made of an insulating plastic rod with the two windings. I don't know what your rubber "princess frog" is, but even if it appears to be rubber (usually an insulator) it might, in fact, be conductive. Make sure by using a high range on the ohmmeter scale of your multimeter to verify that there is no measurable resistance between the copper windings on the two frog legs. My second thought, if the frog is indeed a non-conductor, is to question how your meter range has been selected. It should be in the DCA (direct current amperes) and set to the 200 milliampere range. The negative, or black lead in the COM jack, and the positive (red) lead in the VΩM socket. There also have been some reports on this experiment that some students found that the protective fuse in their multimeter had been blown. Another item to check. Good luck.

Rick Marz

[email protected] · Post by **[email protected]** » Tue Jan 03, 2012 3:44 pm

I have also been struggling with this same experiment. I thought we had the correct connections-but after 2 normal readings for distilled and tap water, the multimeter keeps reading zero, even though I am using DCA in the correct range of 2mA and 20mA. I changed my conductance sensor to a tube that seemed to be rubber and checked the probes. I opened the back of the multimeter and the fuse seems fine. Is there somewhere with a picture of the hookups? The original picture is not very clear. My 9V battery is fine. I have spent hours re-doing. Please any advice. Cathy

After diagramming your connections, they all seem to be correct. Usually this experiment uses a sensor made of an insulating plastic rod with the two windings. I don't know what your rubber "princess frog" is, but even if it appears to be rubber (usually an insulator) it might, in fact, be conductive. Make sure by using a high range on the ohmmeter scale of your multimeter to verify that there is no measurable resistance between the copper windings on the two frog legs. My second thought, if the frog is indeed a non-conductor, is to question how your meter range has been selected. It should be in the DCA (direct current amperes) and set to the 200 milliampere range. The negative, or black lead in the COM jack, and the positive (red) lead in the VΩM socket. There also have been some reports on this experiment that some students found that the protective fuse in their multimeter had been blown. Another item to check. Good luck.

Rick Marz[/quote]

deleted-71882 · Post by **deleted-71882** » Wed Jan 04, 2012 9:08 am

To all Electrolyte Challenge experimenters,

There seems to be many unhappy experimenters doing the Electrolyte Challenge. Here are two pictures of the experimental setup that may be useful.

Figure 1: An example of the setup described in Figure 2 of Electrolyte Challenge. Note that the meter is set to "DC ma" and registers 0.00 ma because the sensor is in air. The sensor is made using copper wire wound on a piece of a plastic pencil barrel. I put a very small drop of "super glue" on each winding to hold it on the barrel securely. My copper wire has a tin coating, so it is silver colored. Bare copper works just the same. The clips are used simply to hold the connections together. Any sort of clip is okay. The rubber bands around the test wires are just to keep them out of the way.

Figure 2: The sensor has been placed in a sample of my tap water. Note that the meter now reads 5.75 ma because my water has electrolytes in it just like commercial drinks have, only it's cheaper

Be sure that the wire you use has no insulation on it. "Magnet wire" may look like bare copper , but it isn't bare.

okl123 · Post by **okl123** » Sat Feb 25, 2012 1:07 pm

im kinda freaking out bc my report is due on monday and i am getting weird results. I am testing water, milk, diet cokem, gatorade, and orange juice and i set the multimeter on the 200mA range. I am getting answers like .1, .5, and .6! Is this rigt? and how to i figure out the electrolyte values from here?

okl123 · Post by **okl123** » Sat Feb 25, 2012 2:14 pm

i put the mulltimeteer on a 9V setting and got answers all around 4.5 range, what do i do

deleted-93346 · Post by **deleted-93346** » Sat Feb 25, 2012 4:00 pm

okl123 wrote:i put the multimeter on a 9V setting and got answers all around 4.5 range, what do i do

I do not know if what you did here was with the probe 1) immersed in the electrolyte or 2) out in the air. But in neither case should you be seeing 4.5 V.

For case 1) you should see 9V, because the very large resistance of the multimeter when set to measure voltage prevents any significant current from flowing, and therefore the E=IR voltage drop from the resistance of the probe in the electrolyte will be zero, and the entire battery voltage will appear at the terminals of the voltmeter. If this is what you did, then either your battery is dead, or your meter is broken (not just a blown fuse).

For case 2) the probe in air is an "open" circuit, that is no current can flow through the loop at all. This is the same as having the voltmeter measure the voltage of the air, so you should see 0 volts. If you see 4.5 volts then the most likely explanation is that your meter is broken (not just a blown fuse).

WW -- if you read this, can you think of any other explanations for the 4.5 V readings?

In the message before your last post you said
"I am testing water, milk, diet cokem, gatorade, and orange juice and i set the multimeter on the 200mA range. I am getting answers like .1, .5, and .6! Is this rigt? and how to i figure out the electrolyte values from here?"
When you see such small readings on a multimeter it means you should change to a more sensitive setting, such as the 20mA range. However, as I noted above, it's likely that your battery and/or your multimeter is dead.

Getting a new battery should be pretty easy. Be SURE never to short out the battery, either by connecting the wire leads from the battery terminal cap together, or, even worse, putting the multimeter probes across the battery when the meter is is set to measure mA. The first case will quickly drain your battery, leaving it partially or wholly discharged (symptom: the voltage across the terminals will be less than 9 V; this is possibly what might have happened in case 1) above. The second case will blow the fuse on the multimeter; however the fact that you were getting readings of 4.5 V according to your second posting seems to indicate that your fuse has not blown.

Any chance that you can borrow another multimeter?

I am sorry that you are experiencing such frustrating difficulties. Experimentation is, indeed, challenging. I hope you persist and find out where the problem lies. Please keep in touch. Also, remember that even if you do not get the "right" answer, if you write up what you did, and the various steps you took to trouble-shoot the experiment, you may well get a decent grade. In my undergraduate days, I not infrequently attempted to perform lab experiments that had been "packaged" with instructions and equipment and failed to get reasonable results. By reporting my efforts fully and honestly I always got good grades anyways, unlike some of my fellow students who attempted to "fudge" their results to agree with what they thought they "should" be. Honesty is of the greatest importance in science. Tolerance for frustration is a prerequisite for all experimenters.

Best of luck!

okl123 · Post by **okl123** » Sun Feb 26, 2012 11:49 am

ok thank you sooooooooooo much, i got a new battery and it worked fine

deleted-93346 · Post by **deleted-93346** » Mon Feb 27, 2012 6:26 am

I am happy that your experiment is now working more as you expected. After all your hard work I hope you get a decent grade! Again, best of luck!