4.6: pH scale for Concentration of Acids and Bases

Exercise \(\PageIndex{1}\)

What is the pH of 4.1 × 10−³ M HCl(aq)? Is this solution acidic or basic?

Answer

\(pH = -log(H^{+})=-log(4.1*10^{-3})=2.39\)

Acidic Solution

Exercise \(\PageIndex{2}\)

What is the pH of a solution that has a H⁺ concentration of 2.4 * 10-9 M. Is this solution acidic or basic?

Answer

pH = 8.62 

Basic Solution

Exercise \(\PageIndex{3}\)

The pH of a vinegar solution is 4.15. What is the H₃O⁺ concentration of the solution?

Answer

Note Hydronium ion, H₃0⁺, and H⁺ are all the same thing.

\(H^{+}=10^{-pH}=10^{-4.15}=7.08 * 10^{-5}M\)

Exercise \(\PageIndex{4}\)

What is the H⁺ concentration of a solution with a pH of 12.05.

Answer

8.91 * 10^-13 M