Electrolyte Challenge Calculations Help

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Electrolyte Challenge Calculations Help

Postby Chemlab » Fri Dec 21, 2012 12:09 pm

For the experiment,
I got an average reading of 42.6 microamps for Gatorade
47.1 microamps for orange juice
8.63 microamps for tap water
and 0 microamps for distilled water
and then for the microamps to siemens conversions, I got
4.72 microsiemens for Gatorade
5.23 microsiemens for Orange Juice
0.959 microsiemens for Tap Water
and 0 microsiemens for distilled water
I am wondering if these results are within the correct range for the experiment, and if I did my microamps to siemens and siemens to microsiemens conversions correctly. The multimeter that I used to get the data was the Equus 3320 Auto-Ranging Digital Multimeter as the link guides to on the website. I am also wondeirng if these results are expected from the Equus 3320 Auto-Ranging Digital Multimeter that I used for my experiment. I am very confused on the accuracy of these results, because I had a lot of trouble and confusion on building the conductance sensor.
Chemlab
 
Posts: 4
Joined: Fri Dec 21, 2012 9:54 am
Occupation: Student:9th Grade
Project Question: Data calculations for the electrolyte challenge; microamps to amps to siemens
Project Due Date: 12/24/12
Project Status: I am finished with my experiment and analyzing the data

Re: Electrolyte Challenge Calculations Help

Postby theborg » Fri Dec 21, 2012 2:04 pm

Chemlab,

Welcome and thank you for your questions. You should get current measurements close to zero for distilled water, but somewhere between 30 and 100 milliamps in some of the drinks. Your readings seem to be about 3 orders of magnitude low. Set your multimeter to the 200 milliamps range, or make sure you aren't mistaking microamps for milliamps. Remember, digital multimeters read back in the range setting they are in. For example, a reading of 1.0 in the 200 milliamp setting is 1.0 milliamps, which equals 0.001 amps (or 1000 microamps). Also, you should get in the range of 2.0 millisiemens for OJ and Sports drink.

Suggestions: Double check your circuit for proper configuration, ensure your multimeter is on the right amp range setting, ensure you use a reasonablely fresh 9V battery for all the tests.

For additional accuracy, if you have access to a second multimeter, you could also measure the DC voltage across the electrodes inserted into the drink specimen and use that value in your calculations instead of just assuming 9V.

As a side note for this type of experiment, there seems to be a relationship between conductivity and temperature of the drink specimen. For even more accuracy, you might consider making sure all your testing fluids are at the same temperature at time of testing as an additional control variable.
I hope this helps.

theborg
----------
"As the circle of light increases, so does the circumference of darkness around it."
~ Albert Einstein
theborg
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Re: Electrolyte Challenge Calculations Help

Postby Chemlab » Fri Dec 21, 2012 4:06 pm

Could it be possible that I used the wrong units, and all of the microamps and microsiemens are actually milliamps and millisiemens. Would that make my data correct?
Chemlab
 
Posts: 4
Joined: Fri Dec 21, 2012 9:54 am
Occupation: Student:9th Grade
Project Question: Data calculations for the electrolyte challenge; microamps to amps to siemens
Project Due Date: 12/24/12
Project Status: I am finished with my experiment and analyzing the data

Re: Electrolyte Challenge Calculations Help

Postby Chemlab » Fri Dec 21, 2012 4:26 pm

Gatorade-1.61 millisiemens
Orange Juice-2.06 millisiemens
Tap water- 0.57 millisiemens
Distilled water- 0 millisiemens
I redid the experiment, but I don't know whether these new results are good or not. A fuse may have broke or something. Please tell me if these results are within correct range.
Chemlab
 
Posts: 4
Joined: Fri Dec 21, 2012 9:54 am
Occupation: Student:9th Grade
Project Question: Data calculations for the electrolyte challenge; microamps to amps to siemens
Project Due Date: 12/24/12
Project Status: I am finished with my experiment and analyzing the data

Re: Electrolyte Challenge Calculations Help

Postby theborg » Fri Dec 21, 2012 7:24 pm

I looks like you are in the right range now. A key component of any scientific experiment is repeatability. I suggest running the experiment at least 2 more times under the same test setup and conditions with new drink samples and see if you get similar results. If they are close, say +/- 5%, then you can take the average of the readings for each sample and report that value as the result. You can also take it a step further and report a sensitivity range. For example, if you measured 3 samples of OJ and came up with 2.00, 2.06, 2.03 millisiemens then your average is 2.03mS +/- 1.5%.
Last edited by theborg on Fri Dec 21, 2012 10:57 pm, edited 3 times in total.
I hope this helps.

theborg
----------
"As the circle of light increases, so does the circumference of darkness around it."
~ Albert Einstein
theborg
Moderator
 
Posts: 220
Joined: Mon Oct 03, 2011 12:26 pm
Occupation: US Air Force Space & Missile Operations
Project Question: "To explain all nature is too difficult a task for any one man. 'Tis much better to do a little with certainty and leave the rest for others that come after you, than to explain all things by conjecture without making sure of anything." - Sir Isaac Newton
Project Due Date: N/A
Project Status: Not applicable

Re: Electrolyte Challenge Calculations Help

Postby Chemlab » Fri Dec 21, 2012 9:48 pm

Thank you so much!!!
Chemlab
 
Posts: 4
Joined: Fri Dec 21, 2012 9:54 am
Occupation: Student:9th Grade
Project Question: Data calculations for the electrolyte challenge; microamps to amps to siemens
Project Due Date: 12/24/12
Project Status: I am finished with my experiment and analyzing the data


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