BioPharm Electrolytes

Strong electrolyte

A compound that dissociates completely into ions in solution

Weak electrolytes

A compound that exists in solution as an equilibrium mixtures of non-ion and ion forms of the molecule

What does equilibrium not mean?

An equal mixture

Weak acids ionize by

Donating a proton to water

WA ionization produces a

H+ and an anion

Weak bases ionize by

Accepting a proton from water

WB ionization produces a

H+ and a non-ion

The RELATIVE concentration of A-/HA or B/BH+ is determined by

The solution pH and compound pKa value

What does the relative concentration of A-/HA or B/BH+ affect?

Solubility, Dissolution Rate, Transport rate across membranes

Common error with weak acids

Their pKa value is less than 7

Common error with weak bases

Their pKa value is greater than 7

Most weak acids are

Carboxylic acids, Phenols, Imides, and Phosphates

Free acid

Has no charge

Henderson-Hasselbalch equation

pH = pKa + log [A-]/[HA]

Ka definition

Equilibrium constant

Ka equation

Ka = ([A-][H+])/[HA]

Ka is used to

Calculate the ratio of [A-]/[HA] at any [H+] concentration

Adding H+ causes

[A-] to decrease and [HA] to increase to maintain Ka as constant

pH is opposite to the

[H+] concentration

“To shift left” or to add an acid (HCl) to a weak acid

Increase [H+] and decrease [A-] and increase [HA]

“To shift right” or to add a base (NaOH) to a weak acid

Decrease [H+] and increase [A-] and decrease [HA}

What contributes to the solution concentration?

Free acid [HA] and anion [A-]