Degree of dissociation accurately defined

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The discussion centers on the concept of the degree of dissociation (alpha) in relation to weak electrolytes. Participants clarify that the degree of dissociation is defined as the fraction of the substance that has dissociated, represented as m/n, where m is the amount that dissociates and n is the initial amount. There is debate over whether n refers to the initial moles of solute or the moles at equilibrium, with the consensus that it can be defined independently of equilibrium conditions. The conversation also touches on the ionic product of water (Kw), noting that it is determined experimentally rather than derived mathematically. Participants emphasize the importance of understanding these definitions clearly and suggest that unrelated questions should be posed in separate threads.
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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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Degree of dissociation is a fraction of substance that dissociated, and it doesn't depend on the amount of substance dissolved.
 
Borek said:
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 ?
 
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.
 
Borek said:
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
 
No contradiction, but a lousy thinking. Ratio doesn't require referring to the amount of substance.
 
Borek said:
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 ?
 
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 said:
You start with n moles, m moles dissociate

ElmorshedyDr said:
"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.
 
  • #10
Borek said:
Perhaps it is time you start paying attention to what you read.
I'm sorry, thanks a lot for you help
 
  • #11
I have a question about the ionic product of water

How is Kw = [ H ] [ OH ] = 10^-14 mole/ liter derived.
 
  • #12
It is not derived, it is determined experimentally.

Please start new threads for new questions.
 

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