(826)在用Ce(SO4)2滴定FeSO4的过程中,在滴定前体系的电极电位由( )决定
A. Ce4+/Ce3+
B. Fe4+/Fe3+
Ce4+/Ce3+和Fe4+/Fe3+
D. O2/H2O
(827)称取NaNO2样品8.0595g溶于500.0mL水中,取25.00mL与50.00mL0.1186mol/LCe4+的强酸溶液相混合,5min后,过量的Ce4+用0.04289mol/L的(NH4)2Fe(SO4)2标准滴定溶液返滴定,用去31.13mL,则样品中NaNO2的质量分数为()。M(NaNO2)=68.995g/mol
A. 15.73%
B. 39.33%
C. 50.76%
D. 78.67%
(828)将0.5000g铁矿石用酸溶解,用还原剂将Fe3+全部还原为Fe2+,然后用0.1000mol/L的Ce(SO4)2标准滴定溶液进行滴定,消耗25.00mL,则矿石中铁的质量分数为()。M(Fe)=55.85g/mol
A. 7.23%
B. 14.46%
C. 28.48%
D. 56.97%
(829)已知c(1/6K2Cr2O7)=0.1200mol/L,那么该溶液对FeO的滴定度为( )mg/mL。M(FeO)=71.84g/mol
A. 8.621
B. 17.24
C. 25.86
D. 51.72