# Determine the solubilities of silver chromate, barium chromate, ferric hydroxide, lead chloride and mercurous iodide at 298K from theor solubility p

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Determine the solubilities of silver chromate, barium chromate, ferric hydroxide, lead chloride and mercurous iodide at 298K from theor solubility product constants given in Table 7.9. Determine also the molarities of individual ions.

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Silver chromate
Ag_(2)CrO_(4), K_(sp) of Ag_(2)CrO_(4)
1.1xx10^(-12)
Let the solution of Ag_(2)CrO_(4) be eauals to S
AgCr_(2)O_(4) hArr 2Ag^(o+)+CrO_(4)^(2-)
1.1xx10^(-12)=(2S)^(2)(S)
or 1.1xx10^(-12)=4S^(3)
or S^(3)=(1.1xx10^(-12))/4
or S=((1.1xx10^(-12))/4)^(1//3)
=0.65xx10^(-4) M
[Ag^(o+)]=2xx0.65xx10^(-4)=1.30xx10^(-4) M
[CrO_(4)^(2-)]=1.3xx10^(-4)//2=6.5xx10^(-5)M
ii. Barium chromate= BaCrO_(4):
BaCrO_(4) hArr Ba^(2+)+CrO_(4)^(2-)
K_(sp) of BaCrO_(4)=1.2xx10^(-10)
or 1.2xx10^(-10)=SxxS
or 1.2xx10^(-10)=S^(2)
or S=sqrt(1.2xx10^(-10))=1.1xx10^(-5) M
iii. Ferric hydroxide: Fe(OH)_(3)
Fe(OH)_(3) hArr Fe^(3+)+3overset(Θ)(O)H
K_(sp) of Fe(OH)(3)=1.0xx10^(-38)
or 1.0xx10^(-38)=Sxx(3S)^(3)
or 1.0xx10^(-38)=27 S^(4)
or S^(4)=(1.0xx10^(-38))/27
or S=((1.0xx10^(-38))/27)^(1//4)=1.39xx10^(-10)M
[Fe^(3+)]=1.39xx10^(-10)M
[overset(Θ)(O)H]=3xx1.39xx10^(-10)=4.17xx10^(-10)M
iv.Lead chloride = PbCl_(2)
PbCl_(2) hArr Pb^(2+)+2Cl^(Θ)
K_(sp) of PbCl_(2)=1.6xx10^(-5)
1.65xx10^(-5)=Sxx(2S)^(2)
or 1.6xx10^(-5)=4S^(3)
or S^(3)=(1.6xx10^(-5))/4=0.4xx10^(-5)
S=(0.4xx10^(-5))^(1//3)=(4xx10^(-6))^(1//3)
=1.59xx10^(-2)M=[Pb^(2+)]
[Cl^(Θ)]=2xx1.59xx10^(-2)=3.18xx10^(-2)M
v. Mercuous iodide: Hg_(2)I_(2)
Hg_(2)I_(2) hArr Hg_(2)^(2+)+2I^(Θ)
K_(sp) of Hg_(2)I_(2)=4/5xx10^(-29)
4.5xx10^(-29)=(S) (2S)^(2)=4S^(3)
or 4.5xx10^(-29)=4S^(3)
or S^(3)=4.5/4xx10^(-29)
or S=(4.5/4xx10^(-29))^(1//3)
=2.24xx10^(-10)M=[Hg_(2)^(2+)]
[I^(Θ)]=2xx2.24xx10^(-10)=4.48xx10^(-10) M.

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