GB 1258-2008Working chemical - Potassium iodate (English PDF)

Foreword

The standard Chapter 4,

5.2.2 are mandatory, other provisions are recommended. This standard replaces GB 1258-1990 "work reference reagent (capacity) of potassium iodate," compared with GB 1258-1990, major changes as follows:

--- Standard name to "work reference reagent potassium iodate";

--- Modify the Content Measurement (1990 version 4.1, this version 5.3). The standard proposed by China Petroleum and Chemical Industry Association. This standard by the National Standardization Technical Committee Chemistry Chemicals Branch (SAC/TC63/SC3) centralized. This standard is drafted by: Beijing Institute of chemical reagents. The main drafters of this standard. Han Baoying, strong Jing Lin. This standard replaces the standards previously issued as follows:

--- GB 1258-1977, GB 1258-1990. Working Standard reagent potassium iodate Warning. some of the test procedure specified in this standard can lead to dangerous situations, the user has the responsibility to take appropriate safety and health practices. Molecular formula. KIO

3 Molecular weight. 214.00 (according to 2005 international relative atomic mass).

1 Scope

China's mandatory national standard for potassium iodate as a working chemical. Potassium iodate is the standard for iodometry, and its usefulness comes from a property the alternative lacks: iodine solutions are unstable, volatile and slowly oxidised by air, so a standard iodine solution cannot be kept - but potassium iodate is a stable solid that liberates an exactly known quantity of iodine when acidified in the presence of iodide, which means the iodine is generated fresh at the moment of use. That makes it the reference for standardising thiosulfate, and thence for every determination of copper, chlorine, sulfite, peroxide and vitamin C that runs through iodometric titration. It is also the compound used to iodise salt, which is a public health measure rather than an analytical one. The standard specifies the requirements, the impurity limits and the test methods for the working grade.

This standard specifies the reference reagent potassium iodate work traits, specifications, testing, packaging and inspection rules and signs. This standard applies to titration analysis work reference reagent potassium iodate test.

2 Normative references

The following documents contain provisions which, through reference in this standard and become the standard terms. For dated references, subsequent Amendments (not including errata content) or revisions do not apply to this standard, however, encourage the parties to the agreement are based on research Whether the latest versions of these documents. For undated reference documents, the latest versions apply to this standard. Preparation of

GB/T 601 chemical reagent standard titration solution

GB/T 602 Determination of impurities in chemical reagents prepared standard solution ( GB/T 602-2002,

ISO 6353-1. 1982, NEQ) with

GB/T 603 chemical reagent test method Preparations of articles ( GB/T 603-2002,

ISO 6353-1 with. 1982, NEQ)

GB/T 609 chemical reagent - General method for determination of total nitrogen ( GB/T 609-2006, ISO 6353-1. 1982, NEQ)

GB/T 6682 analytical laboratory use specifications and test methods ( GB/T 6682-2008, ISO 3696. 1987, MOD)

GB/T 9724 General rule for determination of pH chemical reagent ( GB/T 9724-2007, ISO 6353-1. 1982, NEQ)

GB/T 9728 General method for determination of chemical reagents sulfate ( GB/T 9728-2007, ISO 6353-1. 1982, NEQ)

GB/T 9739 General method for determination of iron chemical reagents ( GB/T 9739-2006,

ISO 6353-1. 1982, NEQ) Determination of working reference reagent content

GB 10737 General Weighing potentiometric titration

GB 15258 rules for preparation of chemical safety labels

3 Characters

This reagent is a white crystalline powder, soluble in water, soluble in ethanol.

4 Specification

Potassium iodate as shown in Table 1. Table

1 Name reference work Content (KIO3), /% 99.95 ~ 100.05 pH value (50g/L, 25 °C) 5.0 ~

5 Test

5.1 General provisions Unless specified otherwise in this chapter, the use of standard titration solution, standard solution, preparations and products, according to GB/T 601, GB/T 602, Regulations preparation, test water should be consistent with GB/T 6682 specifications in three water samples according to precise weighing 0.01g, the use of GB/T 603's Solution "%" are represented by the mass fraction.

5.2 Content Measured according to the provisions of GB 10737.

5.2.1 standard titration with sodium thiosulfate solution titration standard potassium iodate Weigh 0.1g has 180 °C ± 2 °C constant weight standard substance potassium iodate, accurate to 0.00001g, placed in a reaction flask, is dissolved 25mL water, add 3g of potassium iodide and 5mL hydrochloric acid solution (20%), shaken, placed in the dark for 10min, add 150mL water (not to exceed 10 °C), with 213 platinum electrode as the indicator electrode with a 212-type saturated calomel electrode as reference electrode, according to the provisions of GB 10737, with thiosulfate Sulfate standard titration solution [Ba (NaS2O3) = 0.1mol/L] titrated to the end point. Weighing sodium thiosulfate standard titration solution, to be precise 0.0001g. Determination

6 Inspection rules

According to the provisions of HG/T 3921 is sampled and acceptance.

7 Packaging and marking

According to GB 15346 requirements for packaging, storage and transportation, and flags are given, including.