The pOH of a sample of baking soda dissolved in water is \(5.74\) at \(25^{\circ} \mathrm{C}\). Calculate the \(\mathrm{pH},\left[\mathrm{H}^{+}\right]\), and \(\left[\mathrm{OH}^{-}\right]\) for this sample. Is the solution acidic or basic?

Understanding the pH scale is crucial when studying chemistry, as it represents how acidic or basic a solution is. The pH scale ranges from 0 to 14, with 7 being neutral. Numbers below 7 indicate an acidic solution, and numbers above 7 indicate a basic solution. The scale is logarithmic, meaning each whole pH value below 7 is ten times more acidic than the next higher value, and each whole pH value above 7 is ten times less acidic, or more alkaline. In our example, with a pH of 8.26, the solution is considered basic because it is greater than 7.

This scale is directly related to the concentration of hydrogen ions in the solution, allowing us to determine the acidity or basicity through simple calculations.

The concentration of hydrogen ions, denoted as \( [H^+] \), has a direct impact on a solution's pH level. In scientific terms, it is expressed in moles per liter, or molarity. We can calculate \( [H^+] \) by using the inverse logarithm of the pH value: \( [H^+] = 10^{-pH} \). For a pH of 8.26, this results in \( [H^+] = 5.49 \times 10^{-9} \) M. This low concentration of hydrogen ions reflects the basic nature of the solution, as fewer hydrogen ions generally correlate with a higher pH and a more basic solution.

Similarly to hydrogen ions, the concentration of hydroxide ions, written as \( [OH^-] \), is influential in determining the solution's properties. It is measured in the same units as \( [H^+] \), molarity. The relationship between pOH and \( [OH^-] \) is expressed by the formula \( [OH^-] = 10^{-pOH} \). Given a pOH of 5.74, the hydroxide ion concentration is calculated as \( [OH^-] = 1.82 \times 10^{-6} \) M. A higher concentration of hydroxide ions means the solution is more basic, which aligns with our example solution being basic.

Solutions are classified as acidic or basic based on their pH levels. Acidic solutions contain a higher concentration of hydrogen ions and have a pH less than 7. Basic solutions, on the other hand, contain a lower concentration of hydrogen ions and a higher concentration of hydroxide ions, resulting in a pH above 7. Neutral solutions have a pH of exactly 7, indicating a balance in the concentrations of hydrogen and hydroxide ions. In our exercise, a pH of 8.26 indicates that the sample of baking soda dissolved in water is basic, as it has a lower concentration of hydrogen ions and a higher concentration of hydroxide ions compared to a neutral solution.