Which of the following pairs of names and formulas of complexes is not correct?
Answer & explanation
Correct answer: option 3
The correct answer is option 3. Potassium hexacyanidoferrate (III) - K4[Fe(CN)6].
To determine which pair of names and formulas of complexes is not correct, we need to carefully analyze the coordination complexes provided:
1. Tetraamminecopper (II) sulphate - \([Cu(NH_3)_4]SO_4\)
Name: Tetraamminecopper(II) sulphate
Formula: \([Cu(NH_3)_4]SO_4\)
Copper(II) ion (\(Cu^{2+}\)) is coordinated by four ammonia \((NH_3)\) ligands, forming the complex ion \([Cu(NH_3)_4]^{2+}\), which pairs with the sulfate ion (\(SO_4^{2-}\)). This is correct.
2. Diamminesilver (I) chloride - \([Ag(NH_3)_2]Cl\)
Name: Diamminesilver(I) chloride
Formula: \([Ag(NH_3)_2]Cl\)
Silver(I) ion (\(Ag^{+}\)) is coordinated by two ammonia \((NH_3)\) ligands, forming the complex ion \([Ag(NH_3)_2]^{+}\), which pairs with a chloride ion \((Cl^-)\). This is correct.
3. Potassium hexacyanidoferrate (III) - \(K_4[Fe(CN)_6]\)
Name: Potassium hexacyanidoferrate(III)
Formula: \(K_4[Fe(CN)_6]\)
The formula \(K_4[Fe(CN)_6]\) corresponds to the anion \([Fe(CN)_6]^{4-}\), which is actually the hexacyanidoferrate(II) complex. The correct name for \(K_4[Fe(CN)_6]\) is potassium hexacyanidoferrate(II). Therefore, this pair is not correct.
4. Potassium amminepentachloridoplatinate (IV) - \(K[Pt(NH_3)Cl_5]\)
Name: Potassium amminepentachloridoplatinate(IV)
Formula: \(K[Pt(NH_3)Cl_5]\)
Platinum(IV) ion (\(Pt^{4+}\)) is coordinated by one ammonia \((NH_3)\) ligand and five chloride \((Cl^-)\) ligands, forming the complex ion \([Pt(NH_3)Cl_5]^{-}\), which pairs with a potassium ion \((K^+)\). This is correct.
Conclusion: The incorrect pair of name and formula is: Potassium hexacyanidoferrate (III) - \(K_[Fe(CN)_6]\).
The correct name for \(K_4[Fe(CN)_6]\) is potassium hexacyanidoferrate(II).