How to determine anhydrides of acids and bases?

Question

Carter Allen · Accepted Answer

Anhydrides are functional groups which are basically the derivatives of either acids or bases.

Anhydrides are functional groups that are essentially bases or acids' derivatives; bases have no pattern of atomic or molecular connections, whereas acids have the R-COO-CO-R' pattern, where R and R' are alkyl groups.

Nolan Allen · Answer

These are typically oxides of nonmetal, and if an anhydride generates acid(s) when water is added to it, then the anhydride will be an anhydride of acid(s).

As an illustration

1 .#SO_2+H_2O->H_2SO_3#

Here #SO_2# forms #H_2SO_3# when reacted with water . So #SO_2# is anhydride of # H_2SO_3#

2 .#(CH_3CO)_2O+H_2O->2CH_3COOH#

Here #(CH_3CO)_2O# forms #CH_3COOH# when reacted with water . So #(CH_3CO)_2O# is anhydride of # CH_3COOH#

3 .#2NO_2+H_2O->HNO_2+HNO_3#

Here #NO_2# forms #HNO_3 and HNO_2 # when reacted with water . So #NO_2# is mixed anhydride of #HNO_3 and HNO_2 #

(Exception: Some higher valent metallic oxides can form acids when treated with water; they should be treated as anhydride of acid) Anhydrides that produce base when water is added to them are called anhydrides of base. These are generally oxides of metal.

As an illustration

#CaO+H_2O->Ca(OH)_2#

Here #CaO# forms #Ca(OH)_2# when reacted with water . So #CaO# is anhydride of # Ca(OH)_2#

Brooklyn Barber · Answer

undefined Anhydrides of acids and bases can be determined by examining their chemical formulas. Anhydrides of acids are typically formed by removing water from two acid molecules, resulting in the loss of a water molecule. For example, the anhydride of sulfuric acid ($H_2SO_4$) is formed by removing a water molecule, yielding $SO_3$. Anhydrides of bases, on the other hand, are formed by removing water from two base molecules. For instance, the anhydride of sodium hydroxide ($NaOH$) is obtained by removing a water molecule, resulting in $Na_2O$.