Question

Calculate the h3o+ and oh- for 5.0 x 10-3 M HNO3

Answer 1

SAMPLE PROBLEM 18.3

Calculating [H3O+], pH, [OH-], and pOH

PROBLEM:

In a restoration project, a conservator prepares copper-plate etching solutions by diluting concentrated nitric acid, HNO3, to 2.0 M, 0.30 M, and 0.0063 M HNO3. Calculate [H3O+], pH, [OH-], and pOH of the three solutions at 25 oC.

SOLUTION:

For 2.0 M HNO3, [H3O+] = 2.0 M and -log [H3O+] = -0.30 = pH

[OH-] = Kw/ [H3O+] = 1.0 x 10-14/2.0 = 5.0 x 10-15 M; pOH = 14.30

[OH-] = Kw/ [H3O+] = 1.0 x 10-14/0.30 = 3.3 x 10-14 M; pOH = 13.48

For 0.3 M HNO3, [H3O+] = 0.30 M and -log [H3O+] = 0.52 = pH

[OH-] = Kw/ [H3O+] = 1.0 x 10-14/6.3 x 10-3 = 1.6 x 10-12 M; pOH = 11.80

For 0.0063 M HNO3, [H3O+] = 0.0063 M and -log [H3O+] = 2.20 = pH