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Topic: Percent ionization of acids: help needed  (Read 5248 times)

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_Cassie_

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Percent ionization of acids: help needed
« on: June 01, 2005, 11:30:53 PM »
Hey all,

I am trying to work out the following question:

What is the percent ionization of the acid in a 0.0005M solution of acetylsalicyclic acid (aspirin) with a Ka of 3.0 by 10 to the negative 4.

Not sure if this is the way you work it out, but I worked out the [H3O+] and got an answer of 0.019535. I then substituted divided that by the original concentration of the aspirin and multiplied by 100%.

The answer I got was huge, and abviously not right... Can anybody help me?

Cassie.

Offline AWK

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Re:Percent ionization of acids: help needed
« Reply #1 on: June 02, 2005, 01:35:38 AM »
Use unabbreviated Ostwald dilution law and solve quadratic equation
« Last Edit: June 02, 2005, 01:36:20 AM by AWK »
AWK

Offline Borek

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Re:Percent ionization of acids: help needed
« Reply #2 on: June 02, 2005, 06:25:50 AM »
Not sure if this is the way you work it out, but I worked out the [H3O+] and got an answer of 0.019535.

This is obviously wrong - concentration of H+ is larger than the concentration of acid (and we are far from the area where such effect is justified by the water autoionization).
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