氢氧化钠=0.2*0.015=0.003摩尔,能中和硫酸0.003/2=0.0015摩尔；硫酸总量=0.5*0.025=0.0125摩尔,吸收氨气用硫酸0.0125-0.0015=0.011摩尔,生成硫酸铵0.011摩尔,质量=0.011*124=1.364克,硫酸铵的纯度=1.364/1.49=91.5%...