Question

The equation for the pH of a substance is pH = –log[H+], where H+ is the concentration of hydrogen ions. A basic solution has a pH of 11.2. An acidic solution has a pH of 2.4. What is the approximate difference in the concentration of hydrogen ions between the two solutions?
1.6x10^-9
4.0x10^-3
6.7x10-3
1.6x10^11

Answer 1

[H+]_acid = 10^(−2.4) ≈ 3.98×10^(−3) M
[H+]_basic = 10^(−11.2) ≈ 6.31×10^(−12) M

Difference ≈ 3.98×10^(−3) − 6.31×10^(−12) ≈ 3.98×10^(−3) ≈ 4.0×10^(−3).

Answer: 4.0×10^−3.