Write the Ka expression for each of the following in

Solution 8P

Here we have to write the Ka expression for each of the following in water:

Ka is the equilibrium constant . Let us consider the following example to write the expression for Ka.

HA (aq) + H2O (l) ⇆ H3O+ (aq) + A- (aq)

Ka can be written as,

Ka =

Here the concentration of [H2O] is omitted from the expression because it is treated as constant.

Step 1

(a)H2PO4-

Reaction of H2PO4- with water (H2O):-

H2PO4- (aq) + H2O (l) ⇆ H3O+ (aq) + HPO42- (aq)

Thus the expression for Ka is, Ka = .