Sodium hypophosphite is an orthophosphate containing +1 phosphorus, not an acid salt. Most inorganic orthophosphates are neutral, but some are slightly acidic or alkaline. This is mainly due to the difference in the number of hydrogen ions and hydroxide ions produced when they ionize in water. So, what exactly is the acidity/alkalinity of sodium hypophosphite? Let's briefly discuss it below.

Acidity/alkalinity generally refers to the pH value. We generally set the temperature at 25℃. When the pH of a solution is 7, the solution is neutral. When the pH is < 7, the solution is acidic; when the pH is > 7, the solution is alkaline. The acidity/alkalinity of sodium hypophosphite is also tested according to the above definition. Generally, at 20-25℃, the pH value of a 1% or 5% solution is tested, and it is generally around 6-8, which is simply neutral. Strong acids are usually around 0 pH, and strong bases can reach around 15 pH, such as sodium hydroxide and potassium hydroxide.

In sodium hypophosphite acid-base testing, the solution concentration is typically 1-5%, while in practical applications, the aqueous solution concentration can reach 30-50%. How much difference is there between the pH value at such concentrations and the standard value? Actually, the pH change caused by concentration is not significant and can be ignored. Different temperatures may cause slight changes in pH, but in actual industrial production applications, we can also disregard the effect of temperature on pH.