GB/T 2441.5-2010Determination of urea - Part 5: Alkalinity - Titrimetric method (English PDF)

1 Scope

This part of GB/T 2441 specifies the determination of alkalinity in industrial urea by volumetric method.

This part is applicable to the determination of urea alkalinity obtained by synthesis of ammonia and carbon dioxide.

2 normative reference documents

The terms of this document are the terms of this part by reference to this part of GB/T 2441. Any reference to the date of the text , All subsequent amendments (excluding corrigenda) or revisions do not apply to this part, however, encouragement under this section

The parties to the agreement study whether the latest version of these documents can be used. For undated references, the latest edition of this document applies section.

HG/T 2843 chemical analysis of chemical fertilizers commonly used standard titration solution, standard solution, reagent solution and indicator solution

3 principle

The free ammonia of the sample was titrated by titration of the solution with hydrochloric acid in the presence of the indicator liquid.

4 reagents and solutions

The reagents, solutions and water used in this section shall comply with the requirements of HG/T 2843 when not specified and formulated.

5 instruments

Usually laboratory equipment.

6 Analysis steps

Make two samples in parallel.

Approximately 50 g of laboratory samples (accurate to 0.05 g) were weighed and the sample was placed in a 500 mL Erlenmeyer flask and about 350 mL of water was added.

Material, add 3 to 5 drops of mixed indicator solution, and then titrated with hydrochloric acid standard titration solution to the solution was gray green.

7 Analysis of the results of the statement

The alkalinity w is expressed as the mass fraction (%) of ammonia (NH3) and is calculated as follows.

w = c × V × 0.017 × 100m

= c × V × 1.7m

Where.

c - the exact value of the concentration of hydrochloric acid standard titration solution in moles per liter (mol/L);

V - the value of the volume of hydrochloric acid standard titration solution consumed in the measurement, in milliliters (mL);

m - the mass of the sample, in grams (g);

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