[xshadow]

Hi
I have some doubt with this question:

Calculate:

a)the pH of HCl 0,01M at 25 °C, where pkw=14
b)the pH of HCl 0,01M at 100 °C , where pkw=12

I know that:

pH= - log[H⁺]
[H⁺] = C_HCl = 0,01M  (strong acid)

a) pH= 2

But for the b) pint what I have to do?? Why does the exercise give me the two pkw values  at the different temperature?? I have to use that?

thanks

[Borek]

How do you think - does the pKw matter here?

[xshadow]

How do you think - does the pKw matter here?

nothing??

I mean I know that:

[OH^-]*[H⁺]= K_w

In the case b) I should have pkw=12... (so neutrality is when [OH^-]=[H⁺]= 10^-6
But this shouldn't have an effect on pH value...can be the same value of the first question ? 


Thanks.

[AWK]

Compare [H₃O⁺] from water with that of HCl. Is it worthy to take the former into account?

[xshadow]

Compare [H₃O⁺] from water with that of HCl. Is it worthy to take the former into account?

Hi!
mhhh

HCl gives  1*10^-2 H⁺


At 100 °C kw is 10^-12 ...so I have:

H₂O      <----->  H⁺  +  OH^-

-- /  --------------10^-2----0
--/   ------------- +x -----+x

Kw= 10^-12= (10^-2+x ) * x

It's clear that "x" (the water contribute)should be a little number in order to guarantee the ionic product Kw= 1*10^-12  if I have already a 10^-2 


So I think it's negligible... ?