# What is the relationship between pKa and pKb values?

## What is the relationship between pKa and pKb values?

A large Kb value indicates the high level of dissociation of a strong base. A lower pKb value indicates a stronger base. pKa and pKb are related by the simple relation: pKa + pKb = 14.

What pKa is a strong acid?

<-174
Strong acids are defined by their pKa. The acid must be stronger in aqueous solution than a hydronium ion, so its pKa must be lower than that of a hydronium ion. Therefore, strong acids have a pKa of <-174.

Is a higher pKa more acidic?

In addition, the smaller the pKa value, the stronger the acid. For example, the pKa value of lactic acid is about 3.8, so that means lactic acid is a stronger acid than acetic acid.

### How pH relate to pKb?

The smaller pKa, the stronger the acid. The smaller pKb, the stronger the base. Usually pKa is reported for acids and bases – for bases it refers to the conjugate pair. A buffer solution withstands changes in pH when a limited amount of acid or base is added.

What is the relation between pKa of a weak acid and pKb of its conjugate base?

How do you find pH given pKb?

Calculation of the pH of a weak base:

1. Find the [OH-] from the pKb value (in the same way as for weak acid type calculations)
2. From the [OH-] find the pOH.
3. Find the pH from: pOH + pH = 14.

#### What does pKb mean?

pKb is the negative base-10 logarithm of the base dissociation constant (Kb) of a solution. It is used to determine the strength of a base or alkaline solution. pKb = -log10Kb. The lower the pKb value, the stronger the base.

What is the relationship between pKa and acid strength?

The pKa is the pH value at which a chemical species will accept or donate a proton. The lower the pKa, the stronger the acid and the greater the ability to donate a proton in aqueous solution.

What does high pKb mean?

pKa + pKb = 14, so if pKa is low (strong acid) pKb must be high. Therefore, a higher pKb is a stronger acid and a weaker base, and a low pKb is a stronger base and weaker acid.

## What does a high pKb value mean?

A large Kb value means a base has largely dissociated and indicates a strong base. A small pKb value indicates a strong base, while a large pKb value indicates a weak base.

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