Question

Solve this:

$$\begin{gathered} 16.\left(i\right)For{M}^{2+}/Mand{M}^{3+}/M^{2+}systems,E^{0}valuesforsomemetalsareasfollows: \\ C{r}^{2+}/Cr=-0.9VC{r}^{3+}/C{r}^{2+}=-0.4V \\ M{n}^{2+}/Mn=-1.2VM{n}^{3+}/M{n}^{2+}=+1.5V \\ F{e}^{2+}/Fe=-0.4VF{e}^{3+}/F{e}^{2+}=+0.8V \\ Usethisdatatocommentupon \\ \left(a\right)thestabilityofF{e}^{3+}inacidsolutionascomparedtothatofC{r}^{3+}andM{n}^{3+} \\ \left(b\right)theeasewithwhichironcanbeoxidisedascomparedtothesimilarprocessforeitherCrorMnmetals \end{gathered}$$

Answer 1

Dear Student,
(a) From the data given above The E⁰ value of Fe³⁺/Fe²⁺ is more compared to the value of Cr but less than the value for chromium reaction. Due to a negative potential Cr_​³⁺will not easily change to Cr²⁺ so Cr³⁺ is most stable while Mn³⁺ has a large positive value so it can easily change to Mn²⁺.therefore the order of stability is Mn³⁺<Fe³⁺<Cr3+
(b) The reduction potential data shows that the tendency of metals to get oxidized is in the order Fe<Cr<Mn
because Mn has highest value of reduction potential . larger the reduction potential vlue more will be the capability to reduce and more the tendency to get oxidized. So iron has least tendency to get oxidized as per the reduction potential data.
Regards!