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Degree of dissociation accurately defined

by ElmorshedyDr
Tags: accurately, defined, degree, dissociation
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ElmorshedyDr
#1
Apr13-14, 07:56 PM
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Is the degree of dissociation the value of

Alpha when the dissociation begins with 1 mole of the solute, or is it alpha when the solute is 1 mole at equilibrium,



There isn't a difference since I'm talking about very weak electrolytes but I want to know the accurate answer.
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Borek
#2
Apr14-14, 01:50 AM
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Degree of dissociation is a fraction of substance that dissociated, and it doesn't depend on the amount of substance dissolved.
ElmorshedyDr
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Apr14-14, 08:01 AM
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Quote Quote by Borek View Post
Degree of dissociation is a fraction of substance that dissociated, and it doesn't depend on the amount of substance dissolved.

It's said on Wikipedia that is the value of dissociated moles per 1 mole,

It is meant one mole at equilibrium or when the dissociation begins with that 1 moles ?

Borek
#4
Apr14-14, 08:25 AM
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Degree of dissociation accurately defined

I don't care about what wikipedia says. Degree of dissociation is a fraction of the substance that dissociated. You start with n moles, m moles dissociate, degree of dissociation is m/n.
ElmorshedyDr
#5
Apr14-14, 08:43 AM
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Quote Quote by Borek View Post
I don't care about what wikipedia says. Degree of dissociation is a fraction of the substance that dissociated. You start with n moles, m moles dissociate, degree of dissociation is m/n.

Ok, m/n will give the value of m when n is 1, there's no contradiction
Borek
#6
Apr14-14, 09:28 AM
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No contradiction, but a lousy thinking. Ratio doesn't require referring to the amount of substance.
ElmorshedyDr
#7
Apr14-14, 05:37 PM
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Quote Quote by Borek View Post
No contradiction, but a lousy thinking. Ratio doesn't require referring to the amount of substance.

"n moles" is the number of moles at equilibrium or the number of moles that the dissociation starts with ???
DrDu
#8
Apr15-14, 01:26 AM
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The degree of dissociation can be defined independently of equilibrium.
E.g., you could measure it as a function of time after bringing an undissociated substance into a solvent.
Borek
#9
Apr15-14, 02:31 AM
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Quote Quote by Borek View Post
You start with n moles, m moles dissociate
Quote Quote by ElmorshedyDr View Post
"n moles" is the number of moles at equilibrium or the number of moles that the dissociation starts with ???
Perhaps it is time you start paying attention to what you read.
ElmorshedyDr
#10
Apr15-14, 04:26 PM
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Quote Quote by Borek View Post
Perhaps it is time you start paying attention to what you read.

I'm sorry, thanks a lot for you help
ElmorshedyDr
#11
Apr15-14, 04:40 PM
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I have a question about the ionic product of water

How is Kw = [ H ] [ OH ] = 10^-14 mole/ liter derived.
Borek
#12
Apr15-14, 04:48 PM
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It is not derived, it is determined experimentally.

Please start new threads for new questions.


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