Question

(a) Following are the transition metal ions of 3d series:
$T{i}^{4+},V^{2+},M{n}^{3+},C{r}^{3+}$
(Atomic numbers : Ti = 22, V = 23, Mn = 25, Cr = 24)
Answer the following:
(i) Which ion is most stable in an aqueous solution and why?
(ii) Which ion is a strong oxidising agent and why?
(iii) Which ion is colourless and why?
(b) Complete the following equations:
$\left(i\right)2Mn{O}_4^{-}+16H^{+}+5S^{2-}\to \left(ii\right)KMn{O}_4\stackrel{Heat}{\to }$

Answer 1

(a) (i) $C{r}^{3+}$ is most stable, because stabililty depends on electrode potential due to the small size, $C{r}^{3+}$ is most stable.

(ii) $M{n}^{3+}$ because of its half filled configuration.

(iii) $T{i}^{4+},$ because of its d${}^{\circ }$ configuration of the ion.

(b) $\left(i\right)2Mn{O}_4^{-}+16H^{+}+5S^{2-}⟶2M{n}^{2+}+8H_{2}O+5S\left(ii\right)KMn{O}_4\stackrel{Heat}{\to }{K}_{2}Mn{O}_4+Mn{O}_2+O_2\uparrow$