我们用安培滴定法测定钨铁中的钨,利用毫安计按一般程序进行此项工作。在白金皿中放入2.5克钨铁,小心地将它溶于氢氟酸与硝酸的混合液中,溶解时先加入10毫升氢氟酸,然后逐滴加入硝酸,直至合金完全溶解为止。然后,于皿中注入25～30毫升硫酸(1:2),并蒸发到出现SO_a蒸气,冷却带有蒸发残渣H_2WO_4的液体,定量地移入烧杯中,并以30%NaOH溶液中和之,中和后加入过量的硷100毫升,使H_2WO_4以钨酸钠形式转入溶液中。冷却并充份混 We use amperometric titration of tungsten in tungsten and use milliammeter to perform this work according to the general procedure. Place 2.5 grams of ferro-tungsten in a platinum dish and carefully dissolve it in a mixture of hydrofluoric acid and nitric acid. Dissolve 10 ml of hydrofluoric acid and then add nitric acid dropwise until the alloy is completely dissolved. Then, 25 to 30 ml of sulfuric acid (1: 2) is poured into the dish and evaporated until SO_a vapor is present. The liquid with the evaporated residue H_2WO_4 is cooled, transferred quantitatively into a beaker and neutralized with 30% NaOH solution, And after adding an excess of 100 ml of alkaline, H_2WO_4 as sodium tungstate solution into the solution. Cool and mix thoroughly