TITRATING METHOD FOR QUANTITY OF ELECTRICITY OF TOTAL HARDNESS OF SAMPLE

摘要

PURPOSE:To titrate the quantity of electricity easily without skill, by electrolyzing a solution prepared by adding a very small amount of PVA and hydrazine salt to an aqueous solution of copper-EDTA buffered with ammonium salt, and by detecting an end point by a twin-cooper polarization potential difference method. CONSTITUTION:To an aqueous solution of copper-EDTA (copper ethylene-diamine tetraacetate) buffered at a pH of 8.0-9.5 with not less than 0.2M ammonium salt, approximate 0.005% PVA as an electrode stabilizer and 0.03-0.1g of hydrazine salt to 20ml of the above-mentioned solution as a deoxidizing agent are added. The resulting mixture is used as an electrolyte and a sample is added to the mixture and the whole is electrolyzed. An end point at which Cu2+ liberated from the copper- EDTA reduction-expires is detected by a twin-copper polarization potential difference method to obtain the quantity of electricity consumed. The total hardness of the sample is measured on the basis of the quantity of electricity consumed.