Question

Write formulas for the following ions or compounds. (a) diamminetetraquachromium(II) chloride (b) tetrachlorosulfatocadmium(III) (c) sodium tetrahydroxonickelate(II) (d) dibromobis(ethylenediamine)iron(III)

Short answer

Question: Write the formulas for the following coordination complexes and ionic compounds: a) diamminetetraquachromium(II) chloride b) tetrachlorosulfatocadmium(III) c) sodium tetrahydroxonickelate(II) d) dibromobis(ethylenediamine)iron(III) Answer: a) [Cr(NH₃)₂(H₂O)₄]Cl₂ b) [CdCl₄(SO₄)]³⁻ c) Na₂[Ni(OH)₄] d) [Fe(en)₂Br₂]Br

Step-by-step solution

a) diamminetetraquachromium(II) chloride

1. Identify the central metal ion: In this complex, the central metal ion is chromium(II), which means chromium with a +2 oxidation state (Cr²⁺). 2. Identify the ligands: Two types of ligands are present: ammine (NH₃) and aqua (H₂O). There are two ammine ligands (di-) and four aqua ligands (tetra-). 3. Assemble the complex: Put the central metal ion surrounded by the ligands in square brackets, using appropriate number of ligands as indicated: [Cr(NH₃)₂(H₂O)₄]²⁺ 4. Add counter ions: The positive charge on the complex is balanced by the appropriate number of chloride ions (Cl⁻). So, the formula of the compound is [Cr(NH₃)₂(H₂O)₄]Cl₂.

b) tetrachlorosulfatocadmium(III)

1. Identify the central metal ion: In this complex, the central metal ion is cadmium(III), which means cadmium with a +3 oxidation state (Cd³⁺). 2. Identify the ligands: Two types of ligands are present: chloride (Cl⁻) and sulfate (SO₄²⁻). There are four chloride ligands (tetra-) and one sulfate ligand. 3. Assemble the complex: Put the central metal ion surrounded by the ligands in square brackets: [CdCl₄(SO₄)]³⁻ 4. Since this complex is negatively charged, it doesn't need counterions.

c) sodium tetrahydroxonickelate(II)

1. Identify the central metal ion: In this complex, the central metal ion is nickel(II), which means nickel with a +2 oxidation state (Ni²⁺). 2. Identify the ligands: One type of ligand is present: hydroxide (OH⁻). There are four hydroxide ligands (tetra-). 3. Assemble the complex: Put the central metal ion surrounded by the ligands in square brackets: [Ni(OH)₄]²⁻ 4. Add counter ions: The negative charge on the complex is balanced by the appropriate number of sodium ions (Na⁺). So, the formula of the compound is Na₂[Ni(OH)₄].

d) dibromobis(ethylenediamine)iron(III)

1. Identify the central metal ion: In this complex, the central metal ion is iron(III), which means iron with a +3 oxidation state (Fe³⁺). 2. Identify the ligands: Two types of ligands are present: bromide (Br⁻) and ethylenediamine (en, NH₂CH₂CH₂NH₂). There are two bromide ligands (di-) and two ethylenediamine ligands (bis-). 3. Assemble the complex: Put the central metal ion surrounded by the ligands in square brackets, using appropriate number of ligands as indicated: [Fe(en)₂Br₂]³⁺ 4. Add counter ions: The positive charge on the complex is balanced by the appropriate number of bromide ions (Br⁻). So, the formula of the compound is [Fe(en)₂Br₂]Br.