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Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
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limejuice9 limejuice9
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12 years ago
2.) If the pH is 7, what is the hydronium ion concentration?

3.) If the pH is 14, what is the hydronium ion concentration?

4.) If the pH is 3, what is the hydroxide concentration?

5.) If the pH is 8, what is the hydroxide concentration?
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wrote...
#1
12 years ago
ooo my fav qs lol

pH = - log [H30+] remember this. You will need a calculator and understand logarithms (helps to do A level maths Wink Face )   **Note: ILL use   [H+] to mean the hydronium ion.


If the pH = 3, then, using the formula:

     -3 = log [H+]    so   [H+] = 10^-3 = 0.001 M

 when pH = 7:

    -7 = log [H+]   so  [H+] = 10^-7 = 0.0000001 M

see the trick?

     Now for the hydroxide ion -

You need to remember Kw = 10^-14 = [H+][OH-]

and if the pH is 3, then [H+] = 10^-3.  

So 10^-14/10^-3 =   [OH-] = 10^-11 M.

Similarly:
With pH 8,  
   -8 = log [H+]    so [H+] = 10^-8 M

10^-14/10^-8 = 10^-6 M.

And remember  "M" is molarity, that's the conc.  Slight Smile
wrote...
#2
12 years ago
(1) [H3O+] = 1x10^-3
(2) 1x10^-7
(3)1x10^--14
(4) 1x10^-11
(5) 1x10^-6
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