Chemistry 153 6. An unknown cation solution contains either Mg2* or Zn2 ions, wi

Question

Chemistry 153 6. An unknown cation solution contains either Mg2* or Zn2 ions, with nitrate as a counter-ion. Using Winqual, answer the following questions about differentiating these two cations. Don't forget - you can 'right-click' on the solution to get the chemical identity of the species in the solution/solid. a. Create a solution that contains Zn2*, and then add NHs to the solution. What species forms? (circle one) IZn(NHs)4* Zn(OH)26) b. Create a solution that contains Mg2*, and then add NH3 to the solution. What species forms? (circle one) [Mg(NH3)4]2+ Mg(OH)26) Yes No c. Can you use distinguish between Zn2+ and Mg2* ions using NH3?

Explanation / Answer

Mg salts are an esssential part of human nutrition. they are necessary for activity of many enzymes.

a)To make a solution of Zn2+

When NH3(not in excess) is added to Zn2+ ion in aqueous solution

NH3 + Zn2+ + 2H2O ---------> Zn(OH2){white ppt} +2NH4

[ammonia] [zinc ion] [water] [zinc hydroxide]

when more ammonia solution is added, zinc hydroxide forms a complex compound Tetraamminezinc(||) ion. This ion forms a colourless solution.

Zn(OH2) + 4NH3 ------> [Zn(NH3)4]2+{colourless} + 2OH-

[Zinc oxide] [ammonia] [tetraamminezinc(||) ion]

b)To make a solution of Mg2+

When NH3 is added to Mg2+ ion in aqueous solution

NH3 + Mg2+ + 2H2O ---------> Mg(OH2){white ppt} +2NH4

[ammonia] [magnesium ion] [water] [magnesium hydroxide]

when more ammonia solution is added,magnesium hydroxide doesn't form any complex compound . The solution still has white precipitate.

c) From above discusson we conclude that Zn2+ and Mg2+ can be distinguished from each other by using NH3.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.