Draw the products of each reaction and determine the direction of equilibrium.

a.

b.

c.

d.

An equilibrium (the state at which both ‘reactants and products are present in equal concentration) always proceeds toward stable species (least reactive).

The species that can transfer/donate ${\mathrm{H}}^{+}$ions are termed acids, and the species that can accept them are termed bases.

The molecule obtained after the donation of ${\mathrm{H}}^{+}$ions by acid is termed the conjugate base of the acid.

The acceptance of the ${\mathrm{H}}^{+}$ion by a base generates its corresponding conjugate acid.

The ${\mathrm{pK}}_{\mathrm{a}}$values are used to predict the strength of an acid.

The higher the localid="1648549722664" ${\mathbf{pK}}_{\mathbf{a}}$value is, the weaker is the acid.

The products of the given acid-base reactions are as follows:

a.

The acid-base reaction of a

Since the reactant molecule is a weaker acid than its conjugate (on the product side), the equilibrium will lie in the direction of the reactants.

b.

The acid-base reaction of b

The equilibrium lies in the direction of the reactants as a weaker acid is present.

c.

The acid-base reaction of c

Since the conjugate acid is weaker than the acid, the equilibrium will lie in the direction of products.

d.

The acid-base reaction of d

Here, the acid is weaker than its conjugate, so the equilibrium will lie in the direction of the reactants.