What is the equilibrium constant for the reaction of ammonium ion with formate ion?

I know that the ionization constant for ammonium ion is Ka=5.6e-10 and for formate Kb=5.6e-11.

I am not sure what to do next. Should I divide ka by kb?

To determine the equilibrium constant for the reaction between ammonium ion (NH4+) and formate ion (HCO2-), you need to use the concept of the relationship between acid and base ionization constants.

The reaction between ammonium ion and formate ion can be represented as follows:
NH4+ + HCO2- ⇌ NH3 + HCOOH

Since ammonium ion (NH4+) is an acid and formate ion (HCO2-) is a base, their respective ionization constants (Ka and Kb) can be used to find the equilibrium constant (K) for this reaction.

The equilibrium constant (K) is given by the following formula:
K = (Kb / Ka)
where Ka is the acid ionization constant and Kb is the base ionization constant.

In this case, you mentioned that the ionization constant (Ka) for ammonium ion is 5.6e-10, and the ionization constant (Kb) for formate ion is 5.6e-11.

So, to find the equilibrium constant (K), you divide the Kb by Ka:
K = (5.6e-11) / (5.6e-10)

When you divide 5.6e-11 by 5.6e-10, you get:
K ≈ 0.1

Therefore, the equilibrium constant for the reaction of ammonium ion with formate ion is approximately 0.1.

Remember that the equilibrium constant provides information about the balance between the reactants and products at equilibrium. It signifies the relative concentrations of the species involved in the reaction.