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Topic: Rate constant problem  (Read 2724 times)

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Offline nejikun

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Rate constant problem
« on: March 10, 2010, 12:11:08 PM »
The solution of 1 molar HCN (Hydrogen cyanide) has 52% of its molecules separated into H+ and CN-. I have to find the reaction rate constant and then the pH. I only need help with the first part actualyl because finding the pH is easy. I can't find the concentration of HCN, H+ and CN-. thanks in advance!
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Offline Donaldson Tan

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Re: Rate constant problem
« Reply #1 on: March 10, 2010, 12:31:22 PM »
[HCN]0 = [HCN] + [H+] + [CN-]

[HCN]0 = 1.0 M

Given 52% HCN is dissociated, thus
[HCN] = (100% - 52%)*[HCN]0 = 0.48M

I guess you work out the rest from here. It is just material balance.

However, I don't think this is rate constant problem but either an equilibrium constant problem or acid/base dissociation constant problem.
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Offline nejikun

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Re: Rate constant problem
« Reply #2 on: March 10, 2010, 12:48:25 PM »
So the concentration of H+ and CN- will be the square root of the 52%, no?
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