【摘要】 本文采用电势法研究二氧化硫脲还原银氨溶液以沉析银的反应体系。获知体系温度、ｐＨ值、氨含量对反应速度和银沉析率均有较大的影响。在ＮＨ３和Ａｇ＋摩尔比为１８∶１时，体系的最佳反应条件是：ｐＨ＝１２．００，温度为５０℃。在此条件下，将二氧化硫脲溶液不断地加入到［Ａｇ（ＮＨ３）２］＋溶液中，当反应体系的电势降到－７００ｍＶ（ｖｓ．ＳＣＥ）时，停止加入还原剂，并迅速中止反应，此时银的还原沉析率达９９．９％，二氧化硫脲的耗量符合化学计量值。更多还原

【Abstract】 Potential control over precipition of silver from Ag(NH 3) + 2 solution reduced by thiourea dioxe have been studied. The effects of temperature, pH value and the concentration of NH 3 on the rate of the reaction have been examined.The optium reaction conditions is that the molar rate of NH 3 to Ag + is 18∶1,temperature being 50℃,the initial pH of the solution being 12.00.Under such conditions,TD was gradually added to Ag(NH 3) + 2 solution.As soon as the potential of the system dropped to -700mV(vs.SCE), addition of TD was stopped and the solution was quenched quickly.99.8% of silver was reduced from the complex.更多还原