1、INTERNATIONAL STANDARD ISO 6353/2-1983/ADDENDUM 2 Public 1986-11-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION- MEXflYHAPOjJHAfl OPTAHM3ALlMB fl0 CTAHflAPT3ALWWORGANISATION INTERNATIONALE DE NORMALISATION Reagents for Chemical analysis - Part 2: Specifications - First series Mactifs pour analyse
2、s chimigues - Partie 2: Spkifications - Premi VI is the volume, in millilitres, of hydrochloric acid solu- tion used for the titration; Carry out ten titrations and calculate the mean value. PS 30.2.2 Determination of sodium carbonate Dry the sodium carbonate at 285 OC for at least 2 h, then place i
3、t in a desiccator for 30 min. Weigh, to the nearest 0,000 1 g, about 0,93 g of the sodium carbonate, and dissolve it in 150 ml of water. Add, using a 25 ml burette graduated in 0,05 ml divisions and complying with class A of ISO 385/1, 16,00 ml of the hydrochloric acid Solution, cautiously and while
4、 stirring, and then heat to boiling. Cool and titrate, using the same burette, with the same hydrochloric acid Solution according to GM 31.2. Use the same Potentiometer, accurate as in PS 30.2.1. Operate at the calibra- tion temperature of the burette (for example 20 + 1 OC). The assay, expressed as
5、 a percentage by mass of Na2C03, is given by the formula 5,299 4 v-2 c m2 where V2 is the total volume, in millilitres, of hydrochloric acid Solution used for the determination; c is the concentration, in moles of HCI per litre, of hydrochloric acid Solution used ; m2 is the mass, in grams, of sodium carbonate weighed. - Carry out at least ten titrations and calculate the mean value x and the Standard deviation s, using the following equations: N c xi i= 1 x= - N and S= where xi is an individual value; N is the number of values measured.
