Question

The equation for the pH of a substance is pH = -log[H+], where H+ is the concentration of hydrogen ions. What is the approximate pH of a solution whose hydrogen ion concentration is 2 x 10^(-7)?

A. 7
B. 9
C. 5
D. 3

Answer 1

The pH of a solution with a hydrogen ion concentration of 2 x 10^-7 is approximately 6.7, which is closest to option A, pH 7.

Step-by-step explanation:

The student asked about the pH of a solution with a hydrogen ion concentration of 2 x 10-7. To find the pH, we use the equation pH = -log[H+]. Plugging in the hydrogen ion concentration:

pH = -log[2 x 10-7] = -(-7 + log2) ≈ -(-7 + 0.3010) = 7 - 0.3010 ≈ 6.699 Therefore, the approximate pH of the solution is 6.7, which is closest to option A. 7.