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Offline mtcutiepie99

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homework questions asap
« on: 25/01/2005 06:11:08 »
Help would be greatly appreciated!

What class of organic compound is most sensitive to pH changes?

Why does water have a higher boiling point than a nonpolar  liquid like alcohol?

What would you call a solution with a pH of 26?


 

Offline dinesh

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Re: homework questions asap
« Reply #1 on: 16/02/2005 01:40:56 »
alcohols iS polar, due to the OH groups present.
There is no solution with a PH of 26......the highest it goes is 14.
I don't know the answer to the first one, many organic compounds  are sensitive to PH changes
 

Offline nilmot

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Re: homework questions asap
« Reply #2 on: 17/02/2005 13:29:53 »
dinesh,

There could be a solution with a pH value of 26, the value of pH is relied on the concentration of H+ ion present in the solution not just the pH scale.
pH = -log10[H+] (that's to the base 10), the more there are of H+ ions the less the pH. You can even have negative pH in some concentrated acid.

Tom
 

Offline dinesh

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Re: homework questions asap
« Reply #3 on: 18/02/2005 00:34:02 »
Oh my!
I stand corrected.
 

Offline gsmollin

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Re: homework questions asap
« Reply #4 on: 18/02/2005 01:21:20 »
quote:
Originally posted by nilmot

dinesh,

There could be a solution with a pH value of 26, the value of pH is relied on the concentration of H+ ion present in the solution not just the pH scale.
pH = -log10[H+] (that's to the base 10), the more there are of H+ ions the less the pH. You can even have negative pH in some concentrated acid.

Tom



Explain how that works. An acid with a pH of zero would have a concentration of H+ ions of 1 mole/mole. An acid with a pH of -1 would have an H+ concentration of 10 moles/mole. I don't think the math works here. A substrance with a pH of 26 would have a pOH of 14-26=-12. I think the OH- concentration will never approach 1 trillion moles/mole in any substatnce.
 

Offline dinesh

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Re: homework questions asap
« Reply #5 on: 21/02/2005 00:24:53 »
In a solution of Hydron Ion  concentration
1 X 10 ^(-26) , ph=26 :)
 

Offline nilmot

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Re: homework questions asap
« Reply #6 on: 21/02/2005 08:38:03 »
gsmollin,

Physically I'm not sure that solution would exist, but theoretically yes that would be the case.

Tom
 

Offline gsmollin

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Re: homework questions asap
« Reply #7 on: 10/03/2005 17:04:35 »
quote:
Originally posted by dinesh

In a solution of Hydron Ion  concentration
1 X 10 ^(-26) , ph=26 :)




That's not how it works. Your math is ignoring the chemistry, so you get an impossible answer. According to the definition of pH, a pH of 26 gives a pOH of 14-26=-12. The units used in the definitions of pH and pOH ar mole/liter, so some negative numers are allowed, but the negative numbers cannot be far from zero. A pH of 26 gives a pOH of -12, which would be 1 trillion moles/liter concentrated base. There is no such base known.

Look here http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch17/waterframe.html for a development of the pH scale.
« Last Edit: 10/03/2005 17:08:32 by gsmollin »
 

Offline nilmot

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Re: homework questions asap
« Reply #8 on: 12/03/2005 08:57:28 »
Mmm.. that's true

Tom
 

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Re: homework questions asap
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