4.
乙二酸俗称草酸\(\rm{(}\)结构简式为\(\rm{HOOC-COOH}\),可简写为\(\rm{H_{2}C_{2}O_{4})}\),它是一种重要的化工原料\(\rm{.(}\)常温下\(\rm{0.01mol/L}\)的\(\rm{H_{2}C_{2}O_{4}}\)、\(\rm{KHC_{2}O_{4}}\)、\(\rm{K_{2}C_{2}O_{4}}\)溶液的\(\rm{pH}\)如表所示\(\rm{.)}\)
| \(\rm{H_{2}C_{2}O_{4}}\) | \(\rm{KHC_{2}O_{4}}\) | \(\rm{K_{2}C_{2}O_{4}}\) |
\(\rm{pH}\) | \(\rm{2.1}\) | \(\rm{3.1}\) | \(\rm{8.1}\) |
\(\rm{(1)}\)写出\(\rm{H_{2}C_{2}O_{4}}\)的电离方程式___________________________________________;
\(\rm{(2)KHC_{2}O_{4}}\)溶液显酸性的原因是_________________________________________;向\(\rm{0.1mol/L}\)的草酸氢钾溶液里滴加\(\rm{NaOH}\)溶液至中性,此时溶液里各粒子浓度关系正确的是_______.
\(\rm{a.c(K}\)\(\rm{{\,\!}^{+}}\)
\(\rm{)=c(HC}\)\(\rm{{\,\!}_{2}}\)
\(\rm{O}\)\(\rm{{\,\!}_{4}^{-}}\)
\(\rm{)+c(H}\)\(\rm{{\,\!}_{2}}\)
\(\rm{C}\)\(\rm{{\,\!}_{2}}\)
\(\rm{O}\)\(\rm{{\,\!}_{4}}\)
\(\rm{)+c(C}\)\(\rm{{\,\!}_{2}}\)
\(\rm{O}\)\(\rm{{\,\!}_{4}^{2-}}\)
\(\rm{)}\) \(\rm{b.c(Na}\)\(\rm{{\,\!}^{+}}\)
\(\rm{)=c(H}\)\(\rm{{\,\!}_{2}}\)
\(\rm{C}\)\(\rm{{\,\!}_{2}}\)
\(\rm{O}\)\(\rm{{\,\!}_{4}}\)
\(\rm{)+c(C}\)\(\rm{{\,\!}_{2}}\)
\(\rm{O}\)\(\rm{{\,\!}_{4}^{2-}}\)
\(\rm{)}\) \(\rm{c.c(K}\)\(\rm{{\,\!}^{+}}\)
\(\rm{)+c(Na}\)\(\rm{{\,\!}^{+}}\)
\(\rm{)=c(HC}\)\(\rm{{\,\!}_{2}}\)
\(\rm{O}\)\(\rm{{\,\!}_{4}^{-}}\)
\(\rm{)+c(C}\)\(\rm{{\,\!}_{2}}\)
\(\rm{O}\)\(\rm{{\,\!}_{4}^{2-}}\)
\(\rm{)}\) \(\rm{d.c(K}\)\(\rm{{\,\!}^{+}}\)\(\rm{) > c(Na}\)\(\rm{{\,\!}^{+}}\)\(\rm{)}\)
\(\rm{(3)}\)某同学设计实验如图所示:两个烧杯中的试管都分别盛有\(\rm{2mL 0.1 mol/L H_{2}C_{2}O_{4}}\)溶液和\(\rm{4mL 0.1mol/L}\) 酸性\(\rm{KMnO_{4}}\)溶液,分别混合并振荡,记录溶液褪色所需时间\(\rm{.}\)该实验目的是研究__________________________,但该实验始终没有看到溶液褪色,推测原因_________________________________。