Question

The name of anion in the formula ${\text{Ba}}{\left( {{\text{HC}}{{\text{O}}_{\text{3}}}} \right)_{\text{2}}}$ is:
A.Carbonate
B.Bicarbonate
C.Bicarbonite
D.Carbonite

Answer 1

${\text{Ba}}{\left( {{\text{HC}}{{\text{O}}_{\text{3}}}} \right)_{\text{2}}}$ contains ${\text{B}}{{\text{a}}^{2 + }}$ cation and ${\text{HCO}}_3^ -$ anion. ${\text{HCO}}_3^ -$ contains hydrogen, carbon and oxygen atoms. ${\text{HCO}}_3^ -$ is composed of more than one atom and thus, ${\text{HCO}}_3^ -$ is polyatomic. Also, ${\text{HCO}}_3^ -$ has one negative charge and thus, it is a polyatomic anion. Write the name of ${\text{HCO}}_3^ -$ using the rules for naming polyatomic ions.

Complete step by step answer:
${\text{Ba}}{\left( {{\text{HC}}{{\text{O}}_{\text{3}}}} \right)_{\text{2}}}$ contains ${\text{B}}{{\text{a}}^{2 + }}$ cation and ${\text{HCO}}_3^ -$ anion.
${\text{HCO}}_3^ -$ contains a hydrogen atom and a ${\text{CO}}_{\text{3}}^ -$ ion.
The ${\text{CO}}_{\text{3}}^ -$ ion is the carbonate ion.
Thus, the name of ${\text{HCO}}_3^ -$ is hydrogen carbonate.
Prefix “bi-“ is used instead of hydrogen. Thus, hydrogen carbonate is also known as bicarbonate.
Thus, the name of anion in the formula ${\text{Ba}}{\left( {{\text{HC}}{{\text{O}}_{\text{3}}}} \right)_{\text{2}}}$ is bicarbonate.
Therefore, the correct option is B.

Additional Information:
Bicarbonate ion contains three atoms ${\text{H,}}\,{\text{C,}}\,{\text{O}}$ and thus, it is known as a polyatomic ion. The conjugate acid of bicarbonate ion is carbonic acid $\left( {{{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}} \right)$.
Bicarbonate in the form of its sodium salt i.e. sodium bicarbonate $\left( {{\text{NaHC}}{{\text{O}}_{\text{3}}}} \right)$ is commonly known as baking soda.

Note:
Polyatomic ions comprise two or more atoms. One or more oxygen atoms are joined to the main atom with a charge. Ions with a positive charge are cations while the ions with a negative charge are anions.
Rules for naming polyatomic ions are as follows:
Write the name of the first atom.
Determine the number of anions that can be formed by adding oxygen atoms to the main atom.
If the number of oxygen atoms is higher for an element then add suffix “-ate” and if the number of oxygen atoms is lower then add suffix “-ite”.
If the anion contains hydrogen atom in then add the prefix “bi-“ or add “hydrogen” before the name.