Homework Help

Give the rxns for: Zn^2+ + OH^- ---->  and Zn^2+ + OH^- (excess) ---->   What...

user profile pic

spock4 | Student, Undergraduate | (Level 1) Honors

Posted May 1, 2013 at 3:32 AM via web

dislike 1 like

Give the rxns for:

Zn^2+ + OH^- ----> 


Zn^2+ + OH^- (excess) ---->


What excatly made the two diferent? Physically and chemically?

1 Answer | Add Yours

user profile pic

llltkl | College Teacher | (Level 3) Valedictorian

Posted May 1, 2013 at 6:14 AM (Answer #1)

dislike 1 like

Zn^2+ + OH^- ----> Zn(OH)2 (s)

Zn^2+ + OH^- (excess) ----> Zn(OH)4 2˄-

The second reaction may be depicted in a stepwise manner as a result of two successive syeps: Zn^2+ + OH^- ----> Zn(OH)2 (s) --- (i)

Zn(OH)2 + 2OH^- ----> Zn(OH)4˄2- (aq.) --- (ii)

When hydroxide ions are added to a solution of Zn˄2+ ions, white precipitate of Zn(OH)2 is produced. This hydroxide is soluble in acids. Upon addition of excess of alkali (at hydroxide concentration of 0.1 to 1.0M), the precipitate goes into solution, through the formation of a soluble zincate complex, Zn(OH)4 2˄-. The colorless complex ion is tetrahedral in geometry and structurally similar to other ions of zinc e.g. Zn[NH3]4 or Zn[CN]4˄2-, with hydroxide ions in place of NH3 or CN- ions.


Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes