Science Buddies: "Ask an Expert"

Hi, I did the Electrolyte challenge and now I'm not so sure if my results are right. After I averaged each drink's results and divided them by 1,000,000 and by 1,000 ( only the distilled water) as needed and got these numbers:
Gatorade-- .0002, Powerade-- . 00025, Snapple-- .0001, Apple Juice-- .0002, Distilled Water-- 0., Cranberry Juice-- .0002, Propel Zero-- .0001.
BTW I also tested each drink 4 times. Any help would be appreciated. Also, my project is due this Friday. SOS

Hi there,

What is your specific concern? I have never done the experiment so I do not know what kind of values to expect from the measurements. Now you need to calculate conductance. The numbers you listed are the current:

"Calculate the conductance for each liquid by using Equation 1, shown in the Introduction.
The current (I) for each liquid is the average amps that you calculated.
Since the voltage was always from your 9 V battery, you can use 9 V as the voltage (V) in your calculations. In reality, the voltage is likely to be slightly less than 9 V due to internal resistance of the battery. But this change is quite small and nearly constant across the experiment. Because it is so small, you do not need to take it into account. If you have a second multimeter though you can adapt the circuit to monitor both current and voltage across the battery."

"Equation 1. Conductance (siemens) = Current (amps)/Voltage (V)
G = I/V

G is conductance, measured in siemens.
I is current, measured in amperes.
V is the voltage, measured in volts."

Cheers,
Colin

Hey Colin, my concern is that my results so far are too small in comparison to other people's results. But I will plug the numbers into the formula and see what I get. Then I'll post them. Thanks for the help so far.

AmPenn**

Hello AmPenn,

From your post it appears that you divided your multimeter current readings for the drinks by 1,000,000. The distilled water reading was divided by 1000. You might want to check to make sure you divided your readings by the correct factor.

The procedure for the project indicates that you should use the milliamp range on your multimeter for your measurements of tap water and the sports drinks. To convert the milliamp readings to amps, you should divide them by 1000.

For the distilled water reading the procedure indicates that you should use the microamp range on your multimeter. To convert the microamp readings to amps you should divide them by 1,000,000.

If you used the multimeter range settings indicated in the procedure but used the conversion factors described in your post, then the current values for the drinks are low by a factor of 1,000.

I hope this helps. Please ask again if you have more questions.

A. Norman

Hi guys,
On my first post, I made a typo. I actually divided the sport drinks by 1,000 and the distilled water by 1,000,000. Sorry 'bout that. I plugged the Gatorade's average current into the formula in the project's procedure. This is what I got: 2.222222222 times ten to the negative five. Thus the answer is in scientific notation. Is that alright?

AmPenn**

Hi Ampenn,

I'm not sure what the values should look like, but if you're sure you used all the settings and conversions correctly as described in the procedure, then all you can do is report your findings, and if they differ from what others have reported you can hypothesize about why they might be different,

Cheers,
Colin