Question

The equation for the pH of a substance is pH = –log[H+], where H+ is the concentration of hydrogen ions. Which equation models the concentration of hydrogen ions (H+) of a solution whose pH is 7.2?
[H+] = log7.2
[H+] = -log7.2
[H+] = mc014-1.jpg
[H+] = mc014-2.jpg

Answer 1

Start with pH = −log[H+]. For pH = 7.2:

−log[H+] = 7.2 → log[H+] = −7.2 → [H+] = 10^(−7.2).

Numerically, [H+] = 10^(−7.2) ≈ 6.31 × 10^(−8) M.