电镀液中NiSO4 的间接测定法
镀镍溶液NiSO4250g/L=250mg/mL,
取1mL镀液稀至100mL,CNiSO4.6H2O=2.5mg/mL,取稀释液25mL于50mL 烧杯中,加入BaCL2.2H2O溶液(CBaCL2.2H2O=10mg/mL)10mL,生成BaSO4过滤.
取滤液5mL测CBa (必要时稀释),求出质量:
p Ba =CBa测x(25mL+10mL)
(测定中高标和低标中换算成Ba浓度的标准)
高标0.2g=100 mL,即称0.3557g的BaCL2.2H2O定容100 mL容量瓶,再从里边取10 mL定容100 mL容量瓶即为低标.
与(SO4 )2-生成沉淀消耗的Ba质量QBa
Ba消耗量(QBa)= Ba总含量-Ba测出量(p Ba)
QBa=10mg/mLx Ba/BaCL2.2H2Ox10mL-p Ba
=10mg/mLx0.5622x10mL-CBa(测)x35mL
=56.22-22.52=33.7mg
其摩尔数为33.7mg÷1000÷137.33=0.000245
这也是与NiSO4.6H2O生成沉淀的NiSO4.6H2O摩尔数.
25mL稀释镀液中NiSO4.6H2O的质量pNiSO4.6H2O为
pNiSO4.6H2O=0.000245x262.7=0.0644g/25mL
CNiSO4.6H2O=0.0644g/25mL=0.00257g/mL=2.57g/L
原液浓度(因稀释100倍)=257g/L