Question

For a certain solution, the concentration of hydronium ions is greater than the concentration of hydroxide ions. Therefore, the pH of the solution ___________.



a. must be greater than 7.
b. must be less than 7
c. must be exactly 7
d. can either be less than or greater 7, but not equal to 7
e. cannot be predicted in reference to pH 7

Answer 1

b. must be less than 7.

Reason: At 25°C neutral water has [H3O+] = [OH−] = 1.0×10−7 M (pH 7). If [H3O+] > [OH−], the solution is acidic so [H3O+] > 1.0×10−7 M and pH = −log[H3O+] < 7.