What happens to potassium bitartrate (cream of tartar) at temperatures in excess of $\pu{1000\!^\circ F}$? For example, if it is placed on an oven bottom and then run through a self clean cycle.
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2 Answers
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If I remember correctly, tartrates of group 1 and group 2 metals are converted to the corresponding carbonates upon heating ($\pu{1000\!^\circ F = 538^\circ C}$).
In your case, potassium carbonate, $\ce{K2CO3}$, is formed.
(Perhaps, this was a historical route to potassium carbonate, starting from the precipitates found in wine, but I don't have a reference at hand to sopport this assumption.)
answered Oct 20, 2016 at 15:41
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$\begingroup$ Ok. If the K2CO3 continues to be heated, what next? $\endgroup$– BrendanCommented Oct 20, 2016 at 15:57
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$\begingroup$ At the same temperature. An oven clean cycle is around 4 hours and those temperatures are acheived on the cavity bottom in roughly 30 minutes. $\endgroup$– BrendanCommented Oct 20, 2016 at 16:01
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$\begingroup$ @user36348 Melting point of potassium carbonate is around 900 °C. Beyond that, it degrades. $\endgroup$ Commented Oct 20, 2016 at 16:04
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Many of potassium bitartrate's Safety Data Sheets (available online) state that potassium bitartrate decomposes to carbon oxides at high temperatures (carbon monoxide and carbon dioxide), but don't state what that temperature is. Though the vast majority say something like "not determined," a few say it decomposes at temperatures >$200º\mathrm{C}\ (392º\mathrm{C})$. As long as you don't use too much and keep the area around your oven well ventilated, you could probably check this temperature for yourself.
