A solution with a pH of 5 has a concentration of hydrogen ions that is how many times higher than a solution with a pH of 7?

The pH scale is logarithmic, which means that each whole number change on the scale represents a tenfold change in hydrogen ion concentration. A solution with a pH of 7 is considered neutral, with a hydrogen ion concentration of ( 10^{-7} ) moles per liter. When you move to a solution with a pH of 5, which is 2 units lower, the hydrogen ion concentration increases.

To determine how much higher the hydrogen ion concentration is in the pH 5 solution compared to the pH 7 solution, you can calculate it as follows:

• Each decrease of 1 in pH corresponds to a tenfold increase in hydrogen ion concentration. Therefore, moving from a pH of 7 to a pH of 6 increases the concentration by 10 times, and moving from pH 6 to pH 5 increases it by another 10 times.

So the calculation can be summarized as:

From pH 7 to 6: ( 10 \times )

From pH 6 to 5: ( 10 \times )

Multiplying these changes together gives:

( 10 \times 10 = 100 )

Thus, the hydrogen ion