Salts that can ionize out hydrogen ions are usually products in which the hydrogen ions in acids are partially neutralized, such as sodium bicarbonate, potassium bisulfate, etc.

The acid salt solution can be acidic or alkaline. Its acidity or alkalinity depends on the tendency of the acid radical to give or accept electrons. "Giving" is stronger than "accepting" , the aqueous solution is acidic, such as sodium dihydrogen phosphate.

On the contrary, it is alkaline, such as sodium bicarbonate. Acid salts have a wide range of uses. Sodium bicarbonate (also known as baking soda) is used as a foaming agent in industry and daily life. Ammonium bicarbonate can be used as fertilizer. Hydrogen phosphate is the main component of fertilizer.

Judgement of acidity and alkalinity

In layman’s terms, the acid salts of strong acids are acidic, the monosodium salts (or potassium salts) of medium-strong acids are all acidic, and the other sodium salts are acidic. Salts or potassium salts (including the acid salts of all weak acids) are alkaline.

Specific classification:

① Acidic salts whose aqueous solution is acidic Acidic salts of strong bases and strong acids: such as NaHSO4, which is completely ionized in its aqueous solution, so the solution is acidic.

Acidic salts of strong acids and weak bases: salts produced by strong acids and weak bases: such as NH4HSO4, the solution is acidic. The acidity of the solution is due to the ionization of HSO4-. The degree of HSO4- ionization is much greater than that of NH4+ hydrolysis, and it inhibits NH4+ hydrolysis to a certain extent. Therefore, do not think that the acidity comes from the hydrolysis of ammonium roots.

Acidic salts of strong bases and weak acids: The acid radicals are both ionized and hydrolyzed. You need to check the Ka value calculation. However, the acidic salts of medium and strong acids with the first hydrogen ion substituted are basically acidic and contain phenolic hydroxyl and carboxyl groups. Polyacids may not comply.

② Acidic salts whose aqueous solution is alkaline: generally acidic salts of strong base and weak acid, such as: HCO3--salt, HS--salt, because the "ionization" trend is smaller than the "hydrolysis" trend, So the solution is alkaline.