## The Henderson–Hasselbalch Equation

The Henderson–Hasselbalch equation relates the pH of a buffer solution to the initial concentration of its components. Let’s say we have a buffer containing the generic weak acid HA and its conjugate base A–. The dissociation of the acid can … Read more

## The pH of a Buffer Solution

There are two ways of calculating the pH of a buffer solution; the equilibrium approach and the one using the Henderson–Hasselbalch equation. The latter is shorter and is used more often. However, let’s start with the equilibrium approach so that … Read more

## Buffer Solutions

Most solutions change the pH when an acid or a base is added to them. However, for certain reactions and processes, it is necessary to have a system that keeps the pH constant when a certain amount of an acid … Read more

## The pH of Salts With Acidic Cations and Basic Anions

In the previous post couple of posts, we learned how to determine whether the solution of a salt is going to be acidic or basic, and calculate the pH of a salt solution. In short, if the salt is made … Read more

## The pH of a Salt Solution

In the previous post, we learned how to determine whether the solution of a salt is going to be acidic or basic depending on how it was prepared. In short, there is only one step to do this and that … Read more

## Acidity of a Salt Solution

First, recall that a salt is an ionic compound formed by the reaction between an acid and a base where the acid provides the anion, and the base brings the cation to the salt.   HCl(aq) + NaOH(aq) →  NaCl(aq) … Read more

## pH of Polyprotic Acids

Polyprotic acids have more than one dissociable proton, and they dissociate in a stepwise manner. Each dissociation step is characterized by its own acid-dissociation constant, Ka1, Ka2, and so forth. For example, the carbonic acid is a weak, polyprotic acid … Read more

## pH of a Weak Base

In the previous post, we talked about determining the pH of a weak acid. Remember, the main challenge here is that weak acids do not dissociate by 100%, and therefore, the [H+] is not the same as [HA]. To determine … Read more

## pH of a Weak Acid

Determining the pH of a weak acid is more complex compared to what we saw for strong acids, because for a weak acid, the dissociation is not 100%, and therefore, the [H+] is not the same as [HA]. For example: … Read more

## pH + pOH = 14

There is a formula linking the values of pH and pOH which allows determining the pH or pOH based on one another. It is derived from the expression of water ionization, Kw = [H+][OH–]. To get the pH and pOH … Read more

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