An aqueous solution containing one mole of HgI2 and two moles of NaI is orange in colour. On addition of excess NaI the solution becomes colourless. The orange colour reappears on subsequent addition of NaOCl. Explain with equations.

Question

An aqueous solution containing one mole of HgI2 and two moles of NaI is orange in colour. On addition of excess NaI the solution becomes colourless. The orange colour reappears on subsequent addition of NaOCl. Explain with equations. (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

Nal on reaction with Hgl 2 gives a complex salt: 2 NaI + Hgl 2 leftharpoons Na 2[ Hgl 4] The orange colour is due to residual HgI 2. On addition of excess NaI, whole Hgl 2 is converted to complex Na 2[ HgI 4] as colour disappear. The orange colour of HgI 2 reappear duc to conversion of Na 2[ HgI 4] into HgI 2 on treatment with NaOCl. 3 Na 2[ Hgl 4]+2 NaOCl +2 H 2 O longrightarrow 3 HgI 2 +2 NaCl +4 NaOH +2 NaI

Q. An aqueous solution containing one mole of HgI2​ and two moles of NaI is orange in colour. On addition of excess NaI the solution becomes colourless. The orange colour reappears on subsequent addition of NaOCl. Explain with equations.

Q. An aqueous solution containing one mole of $H g I_{2}$ and two moles of $N a I$ is orange in colour. On addition of excess $N a I$ the solution becomes colourless. The orange colour reappears on subsequent addition of $N a OCl$ . Explain with equations.