Question

Will 0.10 M solutions of the following salts be acidic, basic, or neutral?

See Appendix 5 for K_a values.

a. ammonium bicarbonate

b. sodium dihydrogen phosphate

c. sodium hydrogen phosphate

d. ammonium dihydrogen phosphate

e. ammonium formate.

Short answer

1. Ammonium bicarbonate is basic.
2. Sodium dihydrogen phosphate is basic.
3. Sodium hydrogen phosphate is basic.
4. Ammonium dihydrogen phosphate is acidic.
5. Ammonium formate is acidic.

Step-by-step solution

Nature of Ammonium Bicarbonate

K_a of NH₄⁺ =$5.5\times {10}^{-10}$

K_b of HCO₃^- = $1.7\times {10}^{-4}$

As K_b>K_a, ammonium bicarbonate is basic.

Nature of Sodium Dihydrogen Phosphate

As it is a salt of a strong base, i.e., NaOH, and a weak acid, i.e., phosphoric acid, it is a basic salt.

Nature of Sodium Hydrogen Phosphate

As it is a salt of strong a base, i.e., NaOH, and a weak acid, i.e., phosphoric acid, it is a basic salt.

Nature of Ammonium Dihydrogen Phosphate

K_a of NH₄⁺ =$5.5\times {10}^{-10}$

K_b of H₂PO₄^- =role="math" localid="1657521520062" $1.33\times {10}^{-12}$

As K_a> K_b,ammonium dihydrogen phosphate is acidic in nature.

Nature of Ammonium Formate

K_a of NH₄⁺ =$5.5\times {10}^{-10}$

K_b of HCOO^- =$5.5\times {10}^{-11}$

As K_a> K_b,ammonium formate is acidic in nature.