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Old 05-15-2013, 10:28 PM   #1
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Default Dielectric constant of E85?

Anyone here know the dielectric constant of E85?

Gasoline is about 2
E100 is about 24.3

What I don't know is if gasoline mixed with ethanol changes it's properties. If not, then I guess it's just a math equation and I [email protected]
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Old 05-15-2013, 10:57 PM   #2
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Quote:
Originally Posted by emilio700 View Post
Anyone here know the dielectric constant of E85?

Gasoline is about 2
E100 is about 24.3

What I don't know is if gasoline mixed with ethanol changes it's properties. If not, then I guess it's just a math equation and I [email protected]





Quote:
ethanol has a dielectric constant of around 24 at 25 degrees Celsius while gasoline has a dielectric constant of around 2 at the same temperature.

Read more: METHOD FOR TESTING AND CALIBRATING A CAPACITIVE FLEX FUEL SENSOR - Patent application



I'd check the math, if you have the equipment, or an ability to farm it out to a chem lab. Check your local college chem dept?

[more below]
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Old 05-15-2013, 11:02 PM   #3
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Use the baby bottle test to get known e85. Put it in sensor, record value.
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Old 05-15-2013, 11:12 PM   #4
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So, di-electric constant is: how easily the molecule becomes polarized, when exposed to an electrical field.

Water, obviously is highly polarize-able.


IE: The fact that the the two molecules (compounds? It's been a while since chem class) are mixed with each other should not effect how the two react to an electrical field.

So, we have a mixture of 15% gasoline, 85% ethanol. Thus, if he have 1 Liter of e85; we have 150ml of gasoline, and 850ml of ethanol, ASSuming there is no water (or other) contamination.

15% of your solution has a DC of 2, and the other 85% has one of 24.

But, we have to go into moles, to get an accurate percentage.

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Old 05-15-2013, 11:19 PM   #5
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D=m/v

density of gasoline is about .75 kg/l which is 750 grams/liter

750g/l = 750g of gasoline molecules per liter of "gas"

750g/X = 114/1 X = # of moles

6.5789 moles of gasoline.
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Old 05-15-2013, 11:23 PM   #6
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moles you say?
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Dielectric constant of E85?-eastern1.jpg  
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Old 05-15-2013, 11:24 PM   #7
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Quote:
Originally Posted by 2ndGearRubber View Post
So, di-electric constant is: how easily the molecule becomes polarized, when exposed to an electrical field.

Water, obviously is highly polarize-able.


IE: The fact that the the two molecules (compounds? It's been a while since chem class) are mixed with each other should not effect how the two react to an electrical field.

So, we have a mixture of 15% gasoline, 85% ethanol. Thus, if he have 1 Liter of e85; we have 150ml of gasoline, and 850ml of ethanol, ASSuming there is no water (or other) contamination.

15% of your solution has a DC of 2, and the other 85% has one of 24.

But, we have to go into moles, to get an accurate percentage.

[more]
Keep going. We're right now making an example where 10 hours in the library saves you 10 minutes in the lab.
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Old 05-15-2013, 11:25 PM   #8
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We do the same for E85.

D=M/V

801 g/l = 801g of Ethonal per liter of "ethonal"

801/X = 46/1

17.413 moles of ethonal
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Old 05-15-2013, 11:33 PM   #9
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So, within a liter of E85, we have 17.413 moles of ethonal, and 6.5789 moles of gasoline.

17.413 moles, have a DC of 24.3
6.5789 moles, have a DC of 2.0

Total moles of out solution is approx. 23.992 moles. per liter. (molarity, is actually the term, Mr. PSI )

So: 17.413/23.992 = .726 or 72.6% is Ethonal, by mass

27.4% is gasoline, by mass.


[Getting a shower, more to come]
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Old 05-16-2013, 12:08 AM   #10
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2 x .274 = .548

24 x .762 = 18.288

18.836 is the total DC of a solution of E85. As the link I posted earlier states, the likely hood of getting pure E85 is kinda low. Gotta be some water in it.



(I was high as hell through all of AP Chem, use at your own risk)
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Old 05-16-2013, 12:51 AM   #11
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Quote:
Originally Posted by 2ndGearRubber View Post
2 x .274 = .548

24 x .762 = 18.288

18.836 is the total DC of a solution of E85. As the link I posted earlier states, the likely hood of getting pure E85 is kinda low. Gotta be some water in it.



(I was high as hell through all of AP Chem, use at your own risk)

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Old 05-16-2013, 04:17 AM   #12
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Dielectric constants are given at a certain pressure and temperature, or at least that is my understanding. They don't behave in a linear fashion either. I believe in order to get an accurate answer you would need to test your material in the desired conditions.

What's your application that you have worries about?
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Old 05-16-2013, 03:59 PM   #13
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Could make a simple parallel plate capacitor to test it. Charge it with nothing in between, calculate charge on cap, remove battery, put dielectric in between measure voltage. Would need to put a thin layer of insulation around the plates just in case though. Capacitance for parallel plate is ϵ A/d and Charge = V C. Although this is too much work and science
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Old 05-16-2013, 09:10 PM   #14
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You measure capacitance with a capacitance meter.
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Old 05-16-2013, 09:51 PM   #15
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True but I do not think emillio has one which is why I suggested that
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