In chemistry, pOH is a measure of hydroxide ion concentration. The pOH scale is the reverse of the pH scale. pOH and pH are ways of describing how acidic or basic an aqueous solution is. Here is the pOH definition, a look at how pOH and pH are related, and examples of calculating pOH.
pH and pOH are defined as the negative log of hydrogen ion concentration and hydroxide concentration, respectively. pOH is related to pH and can be easily calculated from pH.
While we could also describe the acidity or basicity of a solution in terms of pOH , it is a little more common to use pH . Luckily, we can easily convert between pH and pOH values.
To calculate the pOH of a solution you need to know the concentration of the hydroxide ion in moles per liter (molarity). The pOH is then calculated using the expression:
The pH and pOH scales represent concentrations of [H A 3 O A +] and OH A, respectively. The pH and pOH values of some common substances at standard temperature (25 °C) are shown in this chart.
The pOH scale is similar to the pH scale in that a pOH of 7 is indicative of a neutral solution. A basic solution has a pOH of less than 7, while an acidic solution has a pOH of greater than 7.
Helps quickly determine the pH or pOH for titrations and neutralization reactions. Useful for understanding buffer preparation limits and reaction predictions. Have Questions? If you have any questions, or are looking for more resources, you can join our Discord Server. AP Chem Guide's Crash Course on pH and pOH of Strong Acids and Bases.