lab 4

Question 1

group IV properties?

Answer 1

• reagent: H₂S in presence of NH₄OH
• ions: Ni⁺⁺, Co⁺⁺, Mn⁺⁺
• formulae NiS,CoS,MnS
• distingushing features precipitated as sulfides in presence of NH₄OH by H₂S from ammoniacal sol.

Question 2

•Why did we add NH4OH ?

Answer 2

because the group reagent (NH4)2CO3 is easily hydrolyzed in acidic medium , that`s why we added the NH4OH to make the medium alkaline and avoid the group reagent decomposition .

Question 3

•Why did we add NH4Cl ?

Answer 3

To decrease the concentration of CO₃²- and OH^- by common ion effect to avoid the precipitation of Mg²⁺ (group V) as MgCO₃ or Mg(OH)₂.