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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: Enola on May 02, 2021, 09:38:40 AM

Title: Lead(II) salt - white instead of black
Post by: Enola on May 02, 2021, 09:38:40 AM: Hi. :)

I have a problem. I conducted a reaction in the laboratory: to Na₂S(aq) I added CH₃COOH (high concetration) and then Pb(CH₃COO)₂. But instead of black sediment I got white. And I'm not sure why. Any ideas?
Title: Re: Lead(II) salt - white instead of black
Post by: ACETAT on May 02, 2021, 11:55:29 AM: Are you sure you added lead acetate and not zinc acetate?
Other possibility could be caused by the acetic acid, what happens if you decrease the pH to much .
Title: Re: Lead(II) salt - white instead of black
Post by: Enola on May 02, 2021, 12:32:59 PM: I'm absolutely sure.
The experiment was actually like this: in the test tube no 1 put egg white, add 30% NaOH, then add CH₃COOH (high concetration) and Pb(CH₃COO)₂ - here I got black sediment.
In the test tube no 2 put Na₂S(aq), add CH₃COOH (high concetration) and then Pb(CH₃COO)₂ - here I got white sediment.

My friend did the same experiment and she got the same results.
Title: Re: Lead(II) salt - white instead of black
Post by: Borek on May 02, 2021, 12:51:37 PM: Quote from: Enola on May 02, 2021, 09:38:40 AM
to Na₂S(aq) I added CH₃COOH (high concetration)

It should stink as hell. Did it?

My bet is what you were given as Na₂S was actually not sulfide. Sulfate perhaps? That would fit the white color of the precipitate.
Title: Re: Lead(II) salt - white instead of black
Post by: Enola on May 02, 2021, 01:13:39 PM: Quote from: Borek on May 02, 2021, 12:51:37 PM
Quote from: Enola on May 02, 2021, 09:38:40 AM
to Na₂S(aq) I added CH₃COOH (high concetration)

It should stink as hell. Did it?

Not at all - that also surprised me.