HG/T 2784-2012 Ammonium Sulfite for Industrial Use

The mass fraction of ammonium bisulfite (NH4HSO3), expressed as%, is calculated using formula (2):

=………………………（2）

In the formula:

V — the volume of the sodium hydroxide standard titration solution (4.2.3.2.2) consumed, measured in milliliters (ml);

c—The precise concentration of the standard sodium hydroxide titration solution, measured in molar per liter (mol/L).

M-the molar mass of ammonium bisulfite, measured in grams per mole (g/mol) (M=99.11);

m-the numerical value of the sample mass, in grams (g).

The arithmetic mean of the two parallel test results shall be taken as the test result. The absolute difference between the two parallel test results shall not exceed 0.10%.

4.2.4 Determination of Ammonium Bicarbonate Mass Fraction

4.2.4.1 Principle

According to the principle of acid-base neutralization reaction, methyl red-indigo mixed solution was used as the indicator, and the titration was performed with hydrochloric acid standard titration solution until the solution turned red as the endpoint. The mass fraction of ammonium bicarbonate was calculated based on the consumption of hydrochloric acid standard titration solution.

The reaction is:

NH4HCO3+HCl→NH4Cl+H2O+CO2↑