Qualitative Analysis - Result Question 47
50. $Fe^{3+} \xrightarrow{SCN^{-} \text {(excess) }}$ Blood red $(A) \xrightarrow{F^{-} \text {(excess) }} \text { Colourless }(B)$
Identify $A$ and $B$.
(i) Write IUPAC name of $A$ and $B$.
(ii) Find out spin only magnetic moment of $B$.
(2005)
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Answer:
Correct Answer: 50. ($5.92 $ BM)
Solution:
(i) $Fe^{3+}+3 SCN^{-} \longrightarrow \underset{\substack{\text { Iron (III) thiocyanate} \\ A}}{Fe(SCN) _3}$ (blood red colouration)
$Fe(SCN) _3+F^{-}$(excess) $\longrightarrow \underset{\substack{\text { (Hexafluoroferrate) } \\ B}}{\left[FeF _6\right]^{3-}}+3 SCN^{-}$
(ii) Magnetic moment $\left(\mu _S\right)=\sqrt{n(n+2)}$ $ BM$
$=\sqrt{35}$ $ BM=5.92 $ $BM$
BETA
