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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Dhisbdj on May 14, 2020, 10:11:40 AM

Title: Chemical Equilibrium.
Post by: Dhisbdj on May 14, 2020, 10:11:40 AM
I need help with this question. So i know how to do the calculation part but unfortunately i don’t know how to do the balanced equation for Ka1, Ka2, Ka3.

Calculate the H3O+, H3Cit, H2Cit-, HCit2-, and Cit3- concentrations in an 1.00 M solution of citric acid. (H3Cit: Ka1 = 7.5 x 10-4, Ka2 = 1.7 x 10- 5, Ka3 = 4.0 x 10-7)
Title: Re: Chemical Equilibrium.
Post by: Borek on May 14, 2020, 10:32:34 AM
i don’t know how to do the balanced equation for Ka1, Ka2, Ka3

Huh? How can you know how to calculate anything if you have no idea how constants required to solve the problem are defined?
Title: Re: Chemical Equilibrium.
Post by: Dhisbdj on May 14, 2020, 03:22:53 PM
i don’t know how to do the balanced equation for Ka1, Ka2, Ka3

Huh? How can you know how to calculate anything if you have no idea how constants required to solve the problem are defined?


There was another question like this which i solved and i looked at the answer and it was correct. For this question I’m struggling with doing the balanced equations. The balancing equations for the other questions were easy compared to this.
Title: Re: Chemical Equilibrium.
Post by: Borek on May 15, 2020, 03:05:42 AM
I have no idea what kind of a "balanced equation" (other than the stepwise dissociations, which are trivial) you mean. Please elaborate.
Title: Re: Chemical Equilibrium.
Post by: Dhisbdj on May 15, 2020, 06:23:37 PM
I have no idea what kind of a "balanced equation" (other than the stepwise dissociations, which are trivial) you mean. Please elaborate.

 Yes i meant the dissociations. I solved them but i don’t know if it’s correct.

{H2Cit-} + { H2O} —> {H3Cit} + { OH-}   K1.

{HCit-2} + { H2O} ——> { H2Cit-} + { OH-}  K2.

{ Cit3-} + { H2O} ——> { HCit-2} + {OH-} K3.

Did i do it right ?
Title: Re: Chemical Equilibrium.
Post by: Borek on May 15, 2020, 06:26:01 PM
These are not Ka (acid dissociation constants), these are Kb (base dissociation constants).