Salts of Oxoacids — Definition

Definition

Imagine an acid that contains oxygen, like sulfuric acid ($H_2SO_4$) or nitric acid ($HNO_3$). These are called 'oxoacids' because their acidic hydrogen atoms are attached to oxygen atoms. When these oxoacids react with a base, like a metal hydroxide, the acidic hydrogen atoms are replaced by a metal ion (or ammonium ion, $NH_4^+$), forming a new compound called a 'salt'. If the original acid was an oxoacid, the resulting compound is a 'salt of an oxoacid'.

Think of it this way: an oxoacid has a central atom (like sulfur in $H_2SO_4$ or nitrogen in $HNO_3$) bonded to oxygen atoms, and at least one of these oxygen atoms is also bonded to a hydrogen atom. When this hydrogen atom leaves as a proton ($H^+$), what's left behind is a negatively charged ion called an 'oxoanion'. For example, from $H_2SO_4$, we get $SO_4^{2-}$ (sulfate ion), and from $HNO_3$, we get $NO_3^-$ (nitrate ion).

These oxoanions then combine with positively charged ions (cations) like sodium ($Na^+$), potassium ($K^+$), calcium ($Ca^{2+}$), or ammonium ($NH_4^+$) to form the salts. So, sodium sulfate ($Na_2SO_4$), calcium carbonate ($CaCO_3$), and ammonium nitrate ($NH_4NO_3$) are all examples of salts of oxoacids.

These salts are incredibly important in everyday life and in chemistry. For instance, calcium carbonate is chalk and limestone; sodium bicarbonate is baking soda; nitrates and phosphates are crucial components of fertilizers; and many industrial chemicals are salts of oxoacids.

Understanding their properties, such as how they dissolve in water (solubility), how stable they are when heated (thermal stability), and how they react in redox processes, is fundamental to inorganic chemistry and frequently tested in exams like NEET.