Final answer:
A small difference in pH corresponds to a large change in the concentration of hydronium ions (H3O+), because the pH scale is logarithmic with each unit change representing a tenfold change in ion concentration.
Step-by-step explanation:
A small difference in pH translates to a large change in H3O+ concentration.
The pH scale is logarithmic, meaning each whole number change in pH corresponds to a tenfold change in the concentration of hydronium ions (H3O+). So, if the pH decreases by one unit, the H3O+ concentration increases by a factor of 10; a decrease by two units would result in a 100-fold increase in H3O+ concentration.