What happens to the concentration of H+ ions as the pH of a substance decreases?

When the pH of a substance decreases, the concentration of hydrogen ions (H+) increases. The pH scale is logarithmic, meaning that each whole number change on the scale represents a tenfold change in H+ ion concentration. A decrease in pH indicates a more acidic solution, which corresponds to an increase in the number of H+ ions present.

For example, if the pH drops from 7 to 6, the concentration of H+ ions increases by ten times. This is a fundamental principle of acid-base chemistry, where lower pH values correlate with higher acidity and, consequently, more H+ ions in the solution. Thus, the correct understanding of the relationship between pH and H+ concentration highlights the direct connection: as pH decreases, H+ concentration increases.