JAMB - Chemistry (2024 - No. 24)
The chemical formula for potassiumhexacyanoferrate(II) is
[Fe(CN)\(_6\)]\(^{4-}\)
K\(_3\)Fe(CN)\(_6\)
Fe(CN)\(_6\)
K\(_4\)Fe(CN)\(_6\)
Explicação
Potassium hexacyanoferrate(II) has a complex polymeric structure made up of octahedral [Fe(CN)6]4 centers bonded together by K+ ions. It is a complex salt as well as a
potassium hexacyanoferrate(II) is a bridging ligand (a ligand that bonds to two different metals, forming a bridge between them).
Hexacyano ⇒ 6 molecules of CN. Hence, because CN is negatively charged, it wil also need 6 positively charged ions(metals) to bond with it. However, since ferrate is already said to be ferrate(II), it implies, 4 positive ions will be needed more, and that should be from potassium.
Thus the correct formula for potassium hexacyanoferrate(II) is K\(_4\)Fe(CN)\(_6\)