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Sodium ferrocyanide is used as anti-caking agent in salts and salt substitute. Due to contact with…
Sodium ferrocyanide is used as anti-caking agent in salts and salt substitute. Due to contact with atmospheric moisture, table salt undergoes clumping. Adding certain amount of sodium ferrocyanide can prevent this from occurring.
Consider the coordination compounds $\text{Na}_4[\text{Fe}(\text{CN})_6]$ and $[\text{Fe}(\text{H}_2\text{O})_6]\text{Cl}_2$.
(a)[1.0]
Though cyanide is poisonous, potassium ferrocyanide is used as food additive. Explain.
(b)[1.0]
Which compound will be more stable $\text{Na}_4[\text{Fe}(\text{CN})_6]$ or $[\text{Fe}(\text{H}_2\text{O})_6]\text{Cl}_2$? Justify your answer.
(c)[1.0]
Write the hydrate isomer of $[\text{Fe}(\text{H}_2\text{O})_6]\text{Cl}_2$, which gives one mole of precipitate with $\text{AgNO}_3$ solution.
Answer
Answer (a)
Official answer keyCyanide in $\mathrm{Na_4[Fe(CN)_6]}$ is not ionisable in aqueous solution and hence does not show poisonous effect.
Answer (b)
Official answer key$\mathrm{Na_4[Fe(CN)_6]}$ will be more stable as cyanide is strong ligand and stabilise the compound by pairing the electron in low energy $t_{2g}$ orbitals.
Answer (c)
Official answer key$\mathrm{[Fe(H_2O)_5Cl]Cl.H_2O}$
From ISC 2025 Practice Chemistry, question 87.
Check your working with the Coordination complex analyser: hybridisation, shape, magnetic moment, CFSE, isomers and the IUPAC name of a complex.