What is the pH of a solution with a hydrogen ion concentration of 1 x 10^-4 M?

To determine the pH of a solution, you can use the formula:

[ \text{pH} = -\log[\text{H}^+] ]

In this case, the hydrogen ion concentration ([\text{H}^+]) is given as (1 \times 10^{-4} , \text{M}). Plugging this value into the pH formula yields:

[ \text{pH} = -\log(1 \times 10^{-4}) ]

Calculating the logarithm,

[ \text{pH} = -(-4) = 4 ]

Thus, the pH of the solution is 4. This indicates that the solution is acidic since a pH of less than 7 is characteristic of acidic solutions. The logarithmic scale means that each whole number change in pH represents a tenfold change in hydrogen ion concentration, which is an important concept in understanding the acidity or basicity of a solution.