Q69P - Chemistry: Molecular Nature Of Matter And Change

Question

Give the coordination number of the metal ion and the number of ions per formula unit in each compound in Problem 23.67.

 

Step-by-Step Solution

Answer

$\mathrm{a}) \left(\text{Cr}{\left({\text{H}}_2{\text{O}}_6\right)}_2{\left({\text{SO}}_4\right)}_3\right.$- Coordination number: 6; 5 ions

$\text{b) Ba}(\text{FeBr}4{)}_2$- Coordination number: 4; 11 ions

$\mathrm{c})\left(\text{Pt}{\left(\text{en}\right)}_2\right){\text{CO}}_3$- Coordination number: 4; 2 ions

Step 1: Definition of Coordination Compound

A coordination complex is made up of a core atom or ion, known as the coordination center, which is typically metallic, and an array of attached molecules or ions that are known as ligands or complexing agents.

Step 2: Solve the given statements

The coordination number is the number of ligands directly attached to the central metal ion in a coordination compound. These ligands can be ions, atoms, or molecules. The most common coordination number is 0, but it is also not rare to see 2 and 4 as coordination numbers.

 $\left(\text{Cr}{\left({\text{H}}_2{\text{O}}_6\right)}_2{\left({\text{SO}}_4\right)}_3\right.$- There are six ligands bonded with a central metal ion, so the coordination number is 6. This compound consists of 5 ions (2Cr a+ and $3{\text{SO}}_4^{2-}$).

$\text{Ba}{\left({\text{FeBr}}_4\right)}_2$- There are four ligands bonded with a central metal ion, so the coordination number is 4 This compound consists of 11 ions (Ba+, 2Feand $8{\text{Br}}^{-}$).

$\left(\text{Pt}{\left(\text{en}\right)}_2\right){\text{CO}}_3$- There are two ligands bonded with a central metal ion (en is bidentate), so the coordination number is 4. This compound consists of 2 ions $\left({\text{Pt}}^{2+}\right.$and $\left.{\text{CO}}_3^{2-}\right)$