Standard No.:	GB/T 15057.5-1994
English Name:	Limestone for chemical industry - Determination of silicon dioxide content- Molybdenum blue spectrophotometric method
Chinese Name:	化工用石灰石中二氧化硅含量的测定 钼蓝分光光度法
Professional Classification:	GB    National Standard
Source Content Issued by:	AQSIQ
Issued on:	1994-5-5
Implemented on:	1995-2-1
Status:	valid
Target Language:	English
File Format:	PDF
Word Count:	1500 words
Translation Price(USD):	70.0
Delivery:	via email in 1 business day

1 Subject Content and Application Scope This standard specifies the determination of silicon dioxide content by molybdenum blue spectrophotometric method. This standard is applicable to the determination of silicon dioxide content in limestone products for chemical industry and the determination range is 0.05%~5%. 2 Normative References GB 6682 Water for Analytical Laboratory Use - Specification and Test Methods GB/T 9721 Chemical Reagent - General Rules for the Molecular Absorption Spectrophotometry (Ultraviolet and Visible) 3 Method Summary Melt the specimen with mixed flux of sodium carbonate - boric acid, and then leach with diluted hydrochloric acid. At pH value about 1.1, ammonium molybdate reacts with silicic acid and generates silicon molybdenum heteropoly acid, which is then restored to silicomolybdenum blue with ammonium ferrous sulfate in oxalic acid - sulfuric acid medium by taking ethanol as stabilizer; and measure the absorbance at spectrophotometer wavelength of 680nm.

1 Subject Content and Application Scope 2 Normative References 3 Method Summary 4 Reagents and Solutions 5 Apparatus 6 Specimen 7 Analytical Procedures 8 Plotting of Working Curve 9 Expression of Analysis Results 10 Allowable Difference Additional Information