Advertisements
Advertisements
Question
State your observations when ammonium hydroxide solution is added drop by drop and then in excess to each of the following solutions :
1) Copper sulphate solution
2) Zinc sulfate solution.
Advertisements
Solution
When NH4OH is added to copper sulphate solution drop-wise, a pale blue ppt. is obtained.
CuSO4 + 2NH4OH 
Cu(OH)2 + (NH4)2SO4 + 4H2O
With the excess of NH4OH, the ppt. dissolves to give a deep blue solution of tetraamine copper(II)sulphate
Cu(OH)2 + (NH4)2SO4 + 2NH4OH [Cu(NH3)4]SO4 + 4H2O
2) When NH4OH is added to zinc sulphate solution drop-wise, a white, gelatinous ppt. is obtained.
ZnSO4 + 2NH4OH Zn(OH)2 + (NH4)2SO4
With the excess of NH4OH, the ppt. dissolves to give a colorless solution of tetraamine zinc(II)sulphate.
Zn(OH)2 + (NH4)2SO4 + 2NH4OH [Zn(NH3)4]SO4 + 4H2O
RELATED QUESTIONS
What happens when ammonia solution is added first dropwise and then in excess to the following solution:
CuSO4
Write a balanced equation for this reaction.
Name the metal hydroxides which are soluble in ammonium hydroxide solution.
Name the method used for preparation of the following salt from the list given below:
Zinc ion and Lead ion.
State what do you observe when:
Ammonium hydroxide is added to iron (III) sulphate solution.
State two relevant observation of the following:
Ammonium hydroxide solution is added to copper (II) nitrate solution in small quantities and then in excess
Write the observation for the following:
NaOH is added drop-wise till in excess to a solution of zinc sulphate.
The following table shows the tests a student performed on four different aqueous solutions which are X,Y,Z and W. Based on the observations provided, Identify the cation present
|
Chemical Test |
Observation | Conclusion |
| To Solution X, ammonium hydroxide is added in minium quantity first and then in excess | A dirty white precipitate is formed which dissolves in excess to form a clear solution | (i) |
| To Solution Y, ammonium hydroxide is added in minimum quantity first and then in excess | A pale blue precipitate is formed which dissolves in excess to form a clear inky blue solution | (ii) |
| To solution W, A small quantity of sodium hydroxide solution is added and then in excess | A white precipitate is formed which remains insoluble | (iii) |
| To a salt Z, calcium hydroxide solution is added and then heated | A pungent smelling gas turning moist red litmus paper blue is obtained | (iv) |
Identify the cation in the following case:
Ammonium hydroxide solution when added to Solution B gives a white precipitate which does not dissolve in excess of ammonium hydroxide solution.
Write a balanced equation:
Copper sulphate solution with ammonium hydroxide solution.
Rita was given an unknown salt for identification. She prepared a solution of the salt and divided it into two parts.
- To the first part of the salt solution, she added a few drops of ammonium hydroxide and obtained a reddish-brown precipitate.
- To the second part of the salt solution, she added a few drops of silver nitrate solution and obtained a white precipitate.
Name:
- The cation present and
- The anion present in the salt given for identification.
