The best statement that describes the difference between a substance with a pH of 3.0 and a substance with a pH of 6.0 is:
The substance with the lower pH has 1,000 times as many hydrogen ions per volume of water.
Here's why: pH is a logarithmic scale, specifically based on the concentration of hydrogen ions (\(H^+\)). For every one unit change in pH, the concentration of hydrogen ions changes by a factor of 10. Therefore, a solution with a pH of 3.0 has:
- \(10^{-3}\) moles of \(H^+\) per liter, and
- A solution with a pH of 6.0 has \(10^{-6}\) moles of \(H^+\) per liter.
To compare, you take \(10^{-3} / 10^{-6} = 10^{3} = 1,000\). Thus, the substance with a pH of 3.0 has 1,000 times more hydrogen ions than the substance with a pH of 6.0.