# The concentration of suphide ion in 0.1 M HCl solution saturated with hydrogen sulphide is 1.0xx10^(-19)M. If 10 mL of this is added to 5 mL o

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The concentration of suphide ion in 0.1 M HCl solution saturated with hydrogen sulphide is 1.0xx10^(-19)M. If 10 mL of this is added to 5 mL of 0.04 M solution of the following: FeSO_(4), MnCl_(2), ZnCl_(z) and CdCl_(2). In which of these solutions precipitation will take place?

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For precipitation to take place, it is required that the calculated ionic product exceeds the K_(sp) value.
Before mixing:
{:([S^(2-)]=1.0xx10^(-19)M,[M^(2+)]=0.04M),("volume"=10mL,"volume"=5mL):}
After mixing:
{:([S^(2-)]=?,[M^(2+)]=?),("volume"=(10+5)=15mL,"volume"=15mL):}
[S^(2-)] = (1.0 xx 10^(19) xx 10)/(15) = 6.67 xx 10^(-20) M
[M^(2+)] = (0.04 xx 5)/(15) = 1.33 xx 10^(-2) M
Ionic product = [M^(2+)][S^(2-)]
= (1.33 xx 10^(-2))(6.67 xx 10^(-20))
= 8.87 xx 10^(-22)
This ionic product exceeds the K_(sp) of Zns and CdS. Therefore, precipitation will occur in CdCl_(2) and ZnCl_(2) solutions.