Sodium bicarbonate is CHNaO3 while sodium carbonate is Na2CO3. Simply heat baking soda or sodium bicarbonate in a 200°F oven for about an hour. Carbon dioxide and water will be given off. Dry sodium carbonate will remain.
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Baking soda (Sodium Bicarbonate) slowly turns into washing soda (Sodium Carbonate, a.k.a. soda ash) when heated above 140 degrees F. The carbon dioxide released is what makes things rise. If you heat baking soda to 350-400 degrees, it’ll turn into washing soda fairly quickly.