Block D and F Elements

Kindly go through the answers

(1.25)

${\mathrm{C}\mathrm{r}\mathrm{O}}_4^{2-}+2{\mathrm{H}}^{+}+2{\mathrm{H}}_2{\mathrm{O}}_2?\underset{\text{Chromium Pentoxide}}{{\mathrm{C}\mathrm{r}\mathrm{O}}_5+3{\mathrm{H}}_2\mathrm{O}}$

Chromate ion shape $=$ $$ tetrahedral

But dichromate ion has only one common oxygen bond.

A, B and C can be precipitated by HCl as well as H₂S as their insoluble chlorides and sulphides.

(D) Sn⁺² can be precipitated by H₂S but not by HCl

$S{n}^{+2}+2HCl\to SnC{l}_2\left(soluble\right)$

When Ferric chloride reacts with potassium thiocyanate a blood red colour of Ferric thiocyanate is formed
FeCl? + 3KSCN → Fe (SCN)? + 3KCl

To stop bleeding, FeCl? is applied locally because FeCl? causes denaturation of proteins present in blood. It is a case of coagulation.

$E_{M{n}^{+3}/M{n}^{+2}}^o=1.51V$

the strongest oxidizing agent have the highest reduction potential. So Mn³⁺ is the strongest oxidizing agent.

Cerium exists in two oxidation states (+3) and (+4)

  $\begin{array}{l}C{e}^{+4}+e^{-}\to C{e}^{+3}{E}^0=1.61V\\ C{e}^{+3}+3e^{-}\to Ce{E}^0=-2.336V\end{array}$  

It exist as Ce⁺⁴ and acts like a strong oxidizing agent by gaining electrons

Major components of gun metal are Cu, Sn and Zn