I'd like to make sodium carbonate for ramen noodles. The instructions on the web however vary greatly. One source says to bake baking soda at 350 degrees for 2-5 hours. Others say 250 degrees for an hour. Another says just 200 degrees for an hour.
Does the temperature even matter at all?
How about if I use a higher temperature like 450 degrees? This would be preferable for me as I only need a small amount and I can probably bake it at the same time I'm baking bread.
The temperature needs to be high enough, that's all. 450°F should work fine. (2-5 hours is a little silly, since the reaction is pretty quick once the baking soda itself is up to temperature.)
If you want to check that everything's gone okay, you can weigh the powder before and after. If it's converted properly, its mass should decrease to 63% (EDIT: fixed miscalculation, Matthias' number is the correct one) of the original. (Possibly a little further if there was some moisture in it.)
160 °C (320 °F) for 1-2 h worked for me once, but higher temperatures should not hurt the process.
If you are starting with dry sodium hydrogen carbonate, the mass should reduce to 63 % of the starting mass (more reduction in case of wet starting material).
Explanation for the mass loss number: You are converting two equivalents of sodium hydrogen carbonate with a molar mass of 84.01 g/mol to one equivalent of sodium carbonate with a molar mass of 105.99 g/mol. 105.99/(2*84.01) = 63 %
Scientific American - Vanishing Baking Soda
Just some info to add to the conversation. Was doing research for doing pulled noodles which need an alkaline to help with gluten formation. Came across this article in StackExchange. For me, 270g of Baking Soda was reduced to 184g Sodium Carbonate @ 450 degrees Fahrenheit and was baked for 1.5 hours spread in an aluminum lined 9x9 cake pan. The link to the Scientific American article breaks it down simply; and, added to the great science insight here I think paints a more complete picture.
