Question

Give the formula of each coordination compound. Include square brackets around the coordination complex. Do not include the oxidation state on the metal. Use parentheses only around polyatomic ligands:

(a) Potassium hexacyanoferrate(II)
(b) Sodium diamminedicarbonatoruthenate(III)
(c) Pentaamminechlorochromium(III) chloride

Answer 1

The formulas for the coordination compounds are as follows:

(a) Potassium hexacyanoferrate(II)

The coordination complex is [Fe(CN)6] and it has a charge of -4. The counter-ion is potassium (K+). Therefore, to balance the charge, we need four potassium ions. So, the formula for potassium hexacyanoferrate(II) is K4[Fe(CN)6].

(b) Sodium diamminedicarbonatoruthenate(III)

The coordination complex is [Ru(NH3)2(CO3)2] and it has a charge of -1. The counter-ion is sodium (Na+). Therefore, to balance the charge, we need one sodium ion. So, the formula for sodium diamminedicarbonatoruthenate(III) is Na[Ru(NH3)2(CO3)2].

(c) Pentaamminechlorochromium(III) chloride

The coordination complex is [Cr(NH3)5Cl] and it has a charge of +2. The counter-ion is chloride (Cl-). Therefore, to balance the charge, we need two chloride ions. One chloride is already in the complex, so we only need one more outside of the complex. So, the formula for pentaamminechlorochromium(III) chloride is [Cr(NH3)5Cl]Cl.