论文部分内容阅读
方法要点试样以苛性钠熔融,以硼酸络合氟,在强碱性介质中沉淀钙、镁,使与大量铝分离。将钙、镁沉淀用酸溶解,用三乙醇胺-铜试剂联合掩蔽铁、铝、铜等干扰元素,用 K-B 指示剂以 EDTA 络合滴定钙、镁。操作方法称取0.5000克试料于50毫升银坩埚中,加苛性钠3～4克,置坩埚于450℃左右马弗炉中,缓慢升温至650℃并保温15分钟,取出稍冷,用热水浸洗于300毫升烧杯中(预先加硼酸1克,滤纸浆少许)洗出体积约150毫升。搅拌至硼酸溶解,趁热过滤,用1:10氨水洗烧杯三遍,洗沉淀三遍。弃去滤液。移漏斗于250毫升量瓶上,用1:3热盐酸(近沸)洗沉淀4遍(酸的体积25毫升左右)用热水(近沸)洗沉淀5遍,弃去沉淀,用
Method points Samples were caustic soda melting, boric acid complex fluoride, precipitation of calcium and magnesium in a strong alkaline medium, with a large number of aluminum separation. Calcium and magnesium precipitates are dissolved in acid, triethanolamine-copper reagent is used to mask interference elements such as iron, aluminum and copper, and calcium and magnesium are titrated with K-B indicator by EDTA complexation. Method of operation Weigh 0.5000 grams of sample in 50 ml silver crucible, add caustic soda 3 ~ 4 grams, set the crucible in a muffle furnace at 450 ℃, slowly warmed to 650 ℃ and incubated for 15 minutes, remove the cold, hot Wash the water in a 300 ml beaker (1 g of boric acid in advance, a little filter paper) and wash out about 150 ml. Stirring to dissolve boric acid, filtered while hot, washed with 1:10 ammonia three times, washed three times. Discard the filtrate. Remove the funnel on a 250 ml volumetric flask, wash the pellet 4 times with 1: 3 hot (nearly boiling) acid (about 25 ml volume), wash the pellet 5 times with hot water (near boiling), discard the pellet,