Answer to Question #24159 in Organic Chemistry for dora
how to make carbon dioxide by heating sodium bicarbonate?
Anhydrous sodium carbonate melts at 851 °C (1124 K); however, it gradually decomposes in the temperature range you've specified, according to
Na2CO3(s) = CO2(g) + Na2O(s)
Sodium bicarbonate is even less stable with respect to heating. Solid NaHCO3 begins to lose carbon dioxide and water around 100°C, with complete conversion to sodium carbonate by 200°C:
2NaHCO3(s) = CO2(g) + H2O(g) + Na2CO3(s)