What is the ph of a 6.4× 10–8 m solution of hcl(aq) at 25 °c? report your answer to the hundredths place?

pH = 6.86

Explanation:

Even though HCl is a strong acid, it is so diluted in water that we have to consider the concentration of H+ ions in water.

Thus, pH will be measured after getting total [H+] (adding up [H+] from HCl and water).

[H+] of HCl is given,  6.4× 10^–8

[H+] of water is measured knowing

[H+][OH-] is found by dissosiation of water

H2O -> H+              and           O-

I          6.4× 10^–8                     0

C         +x                                  +x

E         6.4× 10^–8 + x               x

*concentration of H2O removed because its not needed

Kw = [6.4× 10^–8 + x] [x]

10^-14 = [6.4× 10^–8 + x] [x]

do the quadratics...

x= 7.30×10^-8

total [H+] = 6.4× 10^–8 + x

               = (6.4× 10^–8) + (7.30×10^-8)

               = 1.37 × 10^-7

pH = -log[total H+]

pH = -log[1.37 × 10^-7]

ph = 6.86

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