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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: cameron_15 on August 03, 2010, 06:07:59 pm

Title: More than 100% ionisation? What have I done!
Post by: cameron_15 on August 03, 2010, 06:07:59 pm
What Have i done! I've calculated a % ionization of over 100% for a prac we did!

So the concentration of HCl used was 0.01M, the solution had a pH of 1.5 as measured by a pH meter...

When I calculate the % ionization, it comes out to be 316%  :o

So uh, I say it's not possible? Did I break something :2funny:
Title: Re: More than 100% ionisation? What have I done!
Post by: happyhappyland on August 03, 2010, 06:15:13 pm
LOL just write you added the wrong amount of water in ur conclusion
Title: Re: More than 100% ionisation? What have I done!
Post by: cameron_15 on August 03, 2010, 06:19:46 pm
The problem is though, my friends got a similar result!

Maybe the pH meter was poorly calibrated...

Never the less, I'll run with the can't dilute an acid accurately story.
Title: Re: More than 100% ionisation? What have I done!
Post by: Mao on August 03, 2010, 06:20:00 pm
pH meters are very sensitive, so are their calibrated buffer solutions. Unless they are very accurately calibrated with very clean buffer solution, you can get an error of up to pH +/- 1. So that pH=1.5 was probably calibrated by contaminated buffer, what you are looking at is a pH of up to 2 or 2.5, which is okay for 0.01M HCl.
Title: Re: More than 100% ionisation? What have I done!
Post by: Mao on August 03, 2010, 06:21:30 pm
The problem is though, my friends got a similar result!

Maybe the pH meter was poorly calibrated...

Never the less, I'll run with the can't dilute an acid accurately story.

Run with the bolded part.
Title: Re: More than 100% ionisation? What have I done!
Post by: cameron_15 on August 03, 2010, 06:24:28 pm
Sure thing Mao.  thanks for your help!