1.

K_(sp) of Al(OH)_3 is 1 times10^-15 At what pH does 1.0 times 10^-3 M Al^(3+) precipitate on the addition of buffer of NH_4Cl and NH_4OH solution?

Answer»

Solution :`Al(OH)_3 LEFTRIGHTARROW Al^(3+)(aq)+3OH^- (aq)`
`K_(sp)=[Al^(3+)][OH^-]^3`
`Al(OH)_3` PRECIPITATES when
`[Al^(3+)][OH]^3 gtK_(sp)`
`(1 times10^-3)[OH^-]^3gt1 times10^-15`
`[OH]^3 GT 1 times 10^-12`
`[OH] gt1 times10^-4M`
`[OH^-]=1 times10^-4M`
`pOH=-log_10[OH^-]=-LOG( 1 times 10^-4)=4`
`pH=14-4=10`
Thus `Al(OH)_3` precipitates at a pH of 10


Discussion

No Comment Found

Related InterviewSolutions