# Calculate [H3O+] for each solution.(a) pH = 8.55(b) pH = 11.23(c) pH = 2.87(d) pH = 1.22

Chapter 14, Problem 71P

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QUESTION:

Calculate $$\mathrm{[H_3O^+]}$$ for each solution.

(a) pH = 8.55

(b) pH = 11.23

(c) pH = 2.87

(d) pH = 1.22

QUESTION:

Calculate $$\mathrm{[H_3O^+]}$$ for each solution.

(a) pH = 8.55

(b) pH = 11.23

(c) pH = 2.87

(d) pH = 1.22

Solution:

The concentration of [OH-] ion and [H3O+]  can be determined as follows   ,

It is known that pH = -log [H3O+]

-pH = log [H3O+]

10 -pH  = 10log [H3O+]   or

[H3O+] = 10-pH

1.0  10-14

And   [OH-  ]  =  --------------

[H3O+]

Step 1

(a) pH = 8.25

pH = 8.25

The  [H3O+]  from pH =  8.25 can be calculated as follows,

[H3O+] = 10-pH  or  [H3O+] = antilog (- pH)

8.25 = - log [H3O+]

-  8.25 = log [H3O+]

[H3O+] = 10- 8.25  = 5.62 10-9 M

1.0  10-14       1.0  10-14

Thus,  [OH-]  =  -------------- =     -----------    = 1.710-6M

[H3O+]           5.62 10-9

(b) pH = 11.23