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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: romano on July 24, 2008, 10:07:22 PM

Title: Lead sulfate with hydrochloric acid
Post by: romano on July 24, 2008, 10:07:22 PM
I'm wondering what reaction will take place when lead sulfate is mixed with hydrochloric acid?  Will the chloride and sulfur form sulfur dichloride?

Does lead sulfate have a high (basic) pH? 


Thanks for any help on this. 

Title: Re: Lead sulfate with hydrochloric acid
Post by: vhpk on July 25, 2008, 12:09:30 AM
Compare the solubility product of 2 substances above
Title: Re: Lead sulfate with hydrochloric acid
Post by: AWK on July 25, 2008, 02:57:10 AM
Lead sulfate is poorly soluble in water (about 30 mg per liter). Addition of HCl, especially a concnetrated HCl increases solubility of PbSO4.
There are two equilibrium processes that can cause this change
H3O+ + SO42- = H2O + HSO4-
Pb(HSO4)2 and PbCl2 are much better soluble in water than PbSO4 itself.
Moreover in a conc. HCl a formation of a complex anion PbCl3- should be taken into account, but the first reaction is much more important.
Title: Re: Lead sulfate with hydrochloric acid
Post by: vhpk on July 25, 2008, 11:52:07 PM
Quote from: AWK on July 25, 2008, 02:57:10 AM
Lead sulfate is poorly soluble in water (about 30 mg per liter). Addition of HCl, especially a concnetrated HCl increases solubility of PbSO4.
There are two equilibrium processes that can cause this change
H3O+ + SO42- = H2O + HSO4-
Pb(HSO4)2 and PbCl2 are much better soluble in water than PbSO4 itself.
Moreover in a conc. HCl a formation of a complex anion PbCl3- should be taken into account, but the first reaction is much more important.
I think the forming of PbCl42- is more feasible than the one you said
Title: Re: Lead sulfate with hydrochloric acid
Post by: AWK on July 28, 2008, 06:45:49 AM
Quote
I think the forming of PbCl42- is more feasible than the one you said
This is a complex problem. pK4 formation constant for PbCl42- is 1.0 whereus pK3 is 2.04. Its means that formation odf PbCl42- is important only in concentrated Cl- solution.