Chapter 21, Problem 31PS

Interpretation Introduction

Interpretation: To draw the structure of cyclic anion in the salt ${\text{K}}_{\text{3}}{\text{B}}_{\text{3}}{\text{O}}_{\text{6}}$ and the anion in ${\text{Ca}}_{\text{2}}{\text{B}}_{\text{2}}{\text{O}}_{\text{5}}$.

Concept introduction:

${\text{K}}_{\text{3}}{\text{B}}_{\text{3}}{\text{O}}_{\text{6}}$ is a potassium salt of borate. It consists of potassium ion and borate ion. The charge on potassium ion is $+1$. The anion is the compound is ${\text{B}}_{\text{3}}{\text{O}}_{\text{6}}{}^{3-}$. There are three potassium ions in the compound. Thus, the charge on borate ion is $-3$.

${\text{Ca}}_{\text{2}}{\text{B}}_{\text{2}}{\text{O}}_{\text{5}}$ is calcium salt of borate. It consists of calcium ion and borate ion. The anion is the compound is ${\text{B}}_2{\text{O}}_5{}^{2-}$. There are two calcium ions in the compound. The charge on calcium ion is $+2$. Thus, the charge on borate ion is $-4$.