Calculate the pH for each of the following solutions.
a. [H3O+] = 1.0 × 10−6 b. [OH−] = 1.0 ×10−6
a. Because the coeffi cient in the exponential expression for the molar hydronium ion concentration is 1.0, the pH can be obtained from the relationships
[H3O+] = 1.0 × 10−x
pH = x
The power of 10 is -6 in this case, so the pH will be 6.00.
b. The given quantity involves hydroxide ion rather than hydronium ion. Thus we must calculate the hydronium ion concentration first and then calculate the pH.
[H3O+] = 1.0×10−61.00×10−14=1.0×10−8
A solution with a hydronium ion concentration of 1.0 × 10−8 M will have a pH of 8.00.