A) \[0.0307\text{ }M\]
B) \[0.0316M\]
C) \[0.1431\text{ }M\]
D) \[0.1448M\]
Correct Answer: A
Solution :
\[F{{e}^{2+}}\] obtained by reduction of \[F{{e}^{3+}}\] by \[N{{H}_{2}}OH\] is estimated by \[C{{r}_{2}}O_{7}^{2-}\]. \[2N{{H}_{2}}OH+4F{{e}^{3+}}\xrightarrow{{}}{{N}_{2}}O(g)+4F{{e}^{2+}}\] \[+4{{H}^{+}}+{{H}_{2}}O\] \[6F{{e}^{2+}}+C{{r}_{2}}O_{7}^{2-}+14{{H}^{+}}\xrightarrow{{}}6F{{e}^{3+}}\] \[+2C{{r}^{3}}+7{{H}_{2}}O\] \[\frac{\begin{align} & 1C{{r}_{2}}O_{7}^{2-}\equiv 6\,F{{e}^{2+}}\equiv 3N{{H}_{2}}OH \\ & 1mol\,C{{r}_{2}}O_{7}^{2-}\equiv 3\,moloN{{H}_{2}}OH \\ \end{align}}{=\frac{23.61\times 0.0217}{1000}mol\,C{{r}_{2}}O_{7}^{2-}}\] \[=\frac{3\times 23.61\times 0.0217}{1000}mol\,N{{H}_{2}}OH\] \[=1.537\times {{10}^{-3}}mol\,\,N{{H}_{2}}OH\] in \[50mL\] solution Molar concentration of \[N{{H}_{2}}OH\] \[=\frac{1.537\times {{10}^{-3}}}{0.050}=0.0307M\]You need to login to perform this action.
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