Ka

[Karina Rahadian 2G]

A few days ago during lecture, Dr. Lavelle mentioned that Ka is the acidity/ionization/dissociation constant. Can someone explain why Ka can be called the ionization constant or dissociation constant? Thanks!

[Jessa 2K]

Dissociation is defined as the process in which compounds break up into simpler substances that can rearrange themselves into different molecules. So Ka is called the dissociation constant because it is a measure of how many H atoms dissociate or separate from the original molecule to recombine with other molecules. The greater the Ka, the more H atoms dissociate into H3O+ molecules.

[Tina Karami 2K]

There are 2 reactants: H2O and another compound. The Ka is called the ionization constant because the reactant (that is not water) loses a hydrogen ion (H+) and donates it to the H2O to form H3O+. Thus, the reactant is ionized because it loses a proton and now has a negative charge making it an ion. So the name ionization constant refers to this process occurring.

[Hedy Bian 3H]

Ka refers to the ionization constant because it measures the degree of dissociation of hydrogen atoms when an acid is dissolved in water. The higher the Ka, the greater concentration of H3O+ ions are in the solution.

[Valerie Jun 2D]

something is referred to as ionization when a molecule loses its hydrogen atoms and breaks apart to help form other molecules, like H3O+ !

[janice]

Ka can be the ionization and the dissociation constant because the hydrogen atom is detaching, or dissociating, from the molecule. As a result, the two separate species are ionized.

[Emily Ang 2B]

Agreeing with everyone here, ionization can be view as losing or gaining an ion to then alter the charge of the molecule. Hence, why it is also called ionization because in the process of Ka, the acids losses a H+(hydrogen ion) to make the neutral molecule now negative thus creating the H3O+ from the H+ combining with the H2O.

[charliea100]

Any K value (Kc, Kp,Ka,Kb, etc.) is a ratio of products to reactants. When talking about acids and bases, they dissociate to some degree( if they are strong acids/bases, they dissociate completely, and if they are weak acids/bases, they do not dissociate completely). Because strong acids and bases dissociate completely, they typically do not have Ka or Kb values. Ka or Kb values are assigned to weak acids and bases, as they do not completely dissociate. This Ka or Kb value will use the amount dissociated (products) over the amount dissociated (reactants). If one is still a reactant, it has not dissociated.

Hope this helps!