If Ksp of Al ( OH )3 is 1.0 × 10-15 ⋅ M. Find at what pH does 1.0 × 10-3 ⋅ M Al 3+ precipitate on the addition of buffer of NH 4 Cl and NH 4 OH solution.

Question

If Ksp of Al ( OH )3 is 1.0 × 10-15 ⋅ M. Find at what pH does 1.0 × 10-3 ⋅ M Al 3+ precipitate on the addition of buffer of NH 4 Cl and NH 4 OH solution. (A) 10 (B) 10.5 (C) 11 (D) 12

Tardigrade Admin · Accepted Answer

Al ( OH )3( s ) leftharpoons Al ( aq )+3 O overlineH ( aq ) Ksp =[ Al 3+][ O overline H ]3 Al ( OH )3 precipitates when [ Al 3+][ O overlineH ]3> Ksp (1 × 10-3)[ OH -]3>1.0 × 10-15 [ O overline H ]3>1 × 10-12 [ O overline H ]>1 × 10-4 M pOH =- log 1 × 10-4=4 pH =14-4=10

Q. If Ksp of Al(OH)3​ is 1.0×10−15⋅M. Find at what pH does 1.0×10−3⋅MAl3+ precipitate on the addition of buffer of NH4​Cl and NH4​OH solution.

10

10.5

11

12

Al(OH)3​(s)⇌Al(aq)+3OH(aq) Ksp=[Al3+][OH]3 Al(OH)3​ precipitates when [Al3+][OH]3>Ksp (1×10−3)[OH−]3>1.0×10−15 [OH]3>1×10−12 [OH]>1×10−4M pOH=−log1×10−4=4 pH=14−4=10

Q. If $Ks p$ of $A l (O H)_{3}$ is $1.0 \times 1 0^{- 15} \cdot M$ . Find at what $p H$ does $1.0 \times 1 0^{- 3} \cdot M A l^{3 +}$ precipitate on the addition of buffer of $N H_{4} Cl$ and $N H_{4} O H$ solution.