Sodium Hypophosphate acid and alkali characteristic

Sodium hypophosphate (SHPP,NaH2PO2.H2O) CAS:10039-56-2/7681-53-0 is an inorganic compound whose acid and alkali depends on its dissociation behavior in aqueous solution and its reaction with other substances.The following is a detailed analysis of the sodium hypophosphate acid:

1. Chemical properties of sodium hypohosphate

Sodium hypophosphate has the chemical formula NaH2PO2.H2O which contains hypophosphate ion (H2PO2). Secondary phosphate (H3PO2) is a weak acid, and the dissociation reaction is as follows:

H3PO2 ⇌H+ + H2PO2−

Sodium hypophosphate is the sodium salt of hypophosphate, so the acid and alkalinity of its aqueous solution mainly depends on the hydrolysis behavior of the hypophosphate ion (H2PO2).

2. The acid and alkaline of sodium hypophosphate

The acid and alkali of sodium hypophosphate in aqueous solution can be analyzed by the following two aspects:

(1) Hydrolysis of subphosphate ions (H2PO2)

-Subphosphate ions (H2PO2) hydrolysis in water:

H2PO2- + H2O ⇌H3PO2+OH+

-Hydrolysis to generate OH ions, making the solution weakly alkaline.

(2) The acidity of hypophosphoric acid

-Subphosphate (H3PO2) is a weak acid with a weak acidity (pKa 2.0), so the concentration of H ions produced by dissociation in water is low.

-Since sodium hypophosphate is the sodium salt of hypophosphate, H2PO2 ions in its aqueous solution are partially hydrolyzed to produce OH ions, thus making the solution weakly alkaline.

3. PH value of aqueous sodium hypophosphate

-Aqueous sodium hypophosphate is usually weakly alkaline, with pH generally between 8-10.

-The specific pH value depends on the concentration and temperature of the solution. The higher the concentration, the more OH ions produced by hydrolysis, the more alkaline of the solution.

4. Buffering effect of sodium hypophosphate

-Sodium secondary phosphate can form a buffer system with secondary phosphate (H3PO2) to adjust the pH of the solution.

-Buffering is based on the following balance:

H3PO2 ⇌H++ H2PO2-

-When acid (H) is added to the solution, H2PO2 combines with H to form H3PO2, inhibiting the pH decrease.

-When base (OH) is added to the solution, H3PO2 will dissociate to form H, neutralization with OH and inhibit the pH rise.

5. Acid and alkaline application of sodium hypophosphate

The weak alkaline and buffering effect of sodium hypohosphate makes it widely used in the following fields:

-Chemical plating: as a reducing agent, used for chemical nickel plating, its weak alkaline environment contributes to the uniform deposition of the coating layer.

-Water treatment: used to adjust the pH of water to prevent acidic or alkaline.

-Food industry: as a food additive, used to regulate the acid and alkalinity of food.

-Medical field: used to prepare drug buffer solution to maintain the stability of drugs.

6. Summary

The aqueous sodium-hypophosphate is weakly alkaline with pH usually between 8-10.

-Its weakly alkaline originates from the hydrolysis reaction of subphosphate ion (H2PO2).

-Sodium hypophosphate has a certain buffering capacity and can be used to adjust the pH of the solution.

-In practical applications, the acid and alkalinity of sodium hypophosphate is an important basis for its function, especially in chemical plating, water treatment and food industry.