Strong acids: HNO3, H3PO4, HBr Weak acid: NH4Cl Strong bases: LiOH, RbOH Weak base: Na3PO4, (CH3)2NH

1. Classify these compounds by whether they behave as strong acids, weak acids, strong bases, or
weak bases in aqueous solution. Strong acid Weak acid Strong base Weak base (CH3)2NH
NH,CI NagPO4 HNOs H3PO4 LIOH HBr HNs RbOH
Solution
STRONG ACID: HNO 3 , H 3 PO 4 and HBr
WEAK ACID : NH 4 Cl is a salt of strong acid(Hcl) and weak base(NH 4 OH). In aqueous
solution, it undergoes cationic hydrolysis and decreases the OH -
ion concentration, thereby
making the solution acidic. Hence its aqueous solution will be acidic but not as strong as a pure
acid.
STRONG BASE : LiOH and RbOH being hydroxides of 1st group elements are strong bases.
They release OH -
ions in their aqueous solutions and act as strong bases.
WEAK BASE : Na 3 PO 4 is a salt of strong base and weak acid(comparitively weaker then
halogen acids). In aqueous solution, it undergoes anioinic hydrolysis and decreases the
concentration of H +
ions thereby making the solution basic but not as basic as a pure strong base.
Hence the aqueous solution is weakly basic.
(CH 3 ) 2 NH is a weak base as it is an organic compound. It is basic because of the lone pair of
electrons present on N atom of amine group.