[Blade2point0]

Hello,

I am doing a spring semester lab for my sophomore chemistry class and my partner and I need some help.

The experiment was to burn 1 gram of powdered lead tartrate until it turned into a black powder. After some cooling time we were told to dump the product into the air and explain what the black powder was, why it produced a flame when we dumped it, and what the very end product was.

Any input is appreciated and I can provide whatever other details I can if they are needed. Thanks.

[Arkcon]

Well, start with the formula for lead tartrate, and see if you can postulate a guess as to what the reaction was, and what was produced.  This is an old, "trick" of chemistry.  P.S. -- did you really "burn" the lead tartrate, or did you just heat it, it makes a difference.

[Blade2point0]

I am very aware of the difference between heating and burning.
The only chemical equation I am able to create is
PbC₄H₄O₆  :delta: ?

My only guess is that I am burning off hydrogen molecules which would maybe give me

PbC₄H₄O₆  :delta: PbC₄O₆ + 2H₂

I don't know what burning a tartrate should yield, which is why I came to this forum for help.

[Arkcon]

I define burning as a reaction with oxygen.  From the procedure, you might be able to guess, the sample is shielded from oxygen, at least until you tip it out, so it can then react with oxygen in the air.  Also, did you collect and measure hydrogen gas?  Besides which, I don't suspect dry heating an organic compound results in the reaction, or the product you mention.

[Arkcon]

To put it another way, you shouldn't expect free hydrogen gas from roasting a carbon-oxygen-hydrogen compound.  You should instead expect other products, in this case, with an interesting residue remaining.

[Blade2point0]

Hm. This makes sense. Would the product be a combination of the lead, hydrogen, and carbon? Did the burning create carbon dioxide?

[Borek]

Google pyrophoric lead.

[Blade2point0]

Pyrophoric lead is what I was looking for.


Thank you, Borek.

Also thank you, Arkcon, for helping me understand that the sample reacted with oxygen.

[Arkcon]

Can you write the reactions now?

[Blade2point0]

PbC₄H₄O₆ = PbCO₃ + 2H₂ + 3CO ?

[Borek]

Why is lead pyrophoric?

[Blade2point0]

Wow sorry for the late response I have been busy with school.

I am pretty sure the lead is pyrophoric because it takes in oxygen at an intense rate, causing a combustion reaction, this is called oxidizing....I think. So by having the lead carbonate oxidize it turns into lead oxide?

[Arkcon]

No, it wont go that route.  Consider, if you just had tartaric acid, or the even more common, sucrose, and you heated it dry -- what would you end up with?  Carbohydrates decompose to ... what?  What would be left from the decomposition of the transition metal salt of an organic acid?

[Scoth44]

Hey I have the same project. Do you still have the report that you did on it? I'm lost and was wondering if i could have something to reference