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Equations For each one of the four cations, write balanced equations for each re

ID: 103695 • Letter: E

Question

Equations For each one of the four cations, write balanced equations for each reacti occurs. Since the "active ingredient" in combo is NH OH, a reaction with combo is the same reaction as with NH OH. It does not have to be written twice. For convenience you may use either NHs or NH OH for ammonia. Potassium is a spectator ion. It may be on that Bnord in teeuations I no complex forms, write NA at the last requested equation. Reactions involving the magnesium ion Mg2 with NaOH: small amount: excess Mg2 with NH OH (NHs): small amount: excess: Mg 2 with K4[Fe(CN): Mg*2 hydroxide precipitate and HNO Mg" complex ion and HNO Reactions involving the iron(III) ion Fe3 with NaOH: small amount: excess Fe3 with NHOH (NHs): small amount excess: Fe3 with K[Fe(CN Fe3 hydroxide precipitate and HNOs: Fe complex ion and HNO Reactions involving the zine ion Zn*2 with NaOH: small amount: Zn2 with NHOH (NH3): small amount: Zn*2 with K lFe(CN)): excess excess: Zn*2 hydroxide precipitate and HNOs Zn 2 complex ion and HNO Al'3 with NaOH: small amount Al 3 with NHOH (NHs): small amount: Reactions involving the aluminum ion excess: excess: Al' with K [Fe(CN) Alt hydroxide precipitate and HNO: Al complex ion and HNO:

Explanation / Answer

Reaction involving Mg2+ion

The reaction with NaOH

Mg2+(aq) + 2 NaOH (aq) ----> Mg(OH)2 (s) + 2Na+

With NaOH, the Mg2+ is completely precipitated resulting Mg (OH)2, which is insoluble in excess of the NaOH.

The reaction with NH4OH

Mg2+(aq) + 2 NH4OH (aq) <===> Mg(OH)2 + 2 NH4+

Due to the common ion effect magnesium is not precipitated by ammonium hydroxide solution in the presence of ammonium salts. In the presence of a excess NH4+, the ionization of the ammonium hydroxide is depressed to such an extent that the solubility product of Mg(OH)2 is not exceed, hence magnesium is not precipitated

The reaction with K4[Fe(CN)6]

Mg2+(aq) + K4[Fe(CN)6]------> K2Mg[Fe(CN)6]

White, crystalline K2Mg [Fe(CN)6] is formed.

2HNO (aq) + Mg(OH)(s) --->2HO(l) + Mg(NO)(aq)

Mg(OH)(s) dissolve in HNO.

Mg2+ complex ion + HNO ---> NA

Magnesium ion rarely forms complex ions.

Reaction involving iron(III) ion

Fe3+(aq) + 3 NaOH(aq) ==> Fe(OH)3 + 3Na+

Orange solid formed, which is not dissolved in excess NaOH

Fe3+(aq) + 3 NH4OH(aq) ==> Fe(OH)3(s) + 3NH4OH

Fe3+ + K4[Fe(CN)6] KFe[Fe(CN)6] + 3K+

Fe(OH)3(s) + 3 HNO3(aq) = Fe(NO3)3(aq) + 3 H2O(l

Reaction involving Zn2+ion

With NaOH

Zn2+(aq) + 2 NaOH(aq) ==> Zn(OH)2 + 2Na+

With excess NaOH

With excess NaOH a complex is formed, which is water soluble.
Zn(OH)2(s) + 2NaOH(aq) 2Na+(aq) + Zn(OH)4 ²¯(aq)

Reaction involving Al3+ion

With NaOH

Al3+(aq) + 3 NaOH(aq) ==> Al(OH)3 + 3Na+

Aluminum ion reacts with aqueous ammonia to produce a white gelatinous precipitate of Al(OH)3

With excess NaOH a complex is formed, which is soluble.

Al(OH)3(s) + OH-(aq) <==> Al(OH)4-(aq)

With 3NH3

Al3+(aq) +)+ 3H2O(aq) <==> Al(OH)3(s) + 3NH4+(aq)

HNO3(aq)+Al(OH)3(s) ---> NA