Question

Determine whether an aqueous solution of each of the following salts will be acidic, basic, or neutral. Ba3(PO4)2 NaCN

Answer 1

This salt will dissociate as follows

Now, the cation will react with water to form

Note that Ba(OH)2 is a strong base and will completely ionize in water. Hence, there will be no net effect on pH because of Ba2+ cation.

Now, the anion will react with water as follows

Now, the phosphoric acid formed here is a weak acid. Hence, it will not completely hydrolyze in water, which means we will have more OH- ions in the salt solution owing to the above equation. Hence, the aqueous solution of will be basic.

This salt will dissociate as follows

Now, the cation will react with water to form

Note that NaOH is a strong base and will completely ionize in water. Hence, there will be no net effect on pH because of Na+ cation.

Now, the anion will react with water as follows

Now, the hydrocyanic acid formed here is a weak acid. Hence, it will not completely hydrolyze in water, which means we will have more OH- ions in the salt solution owing to the above equation. Hence, the aqueous solution of NaCN will be basic.

Hence, the aqueous solutions of Ba3(PO4)3 and NaCN will be basic.