Abstract From the perspective of chemical thermodynamics, through calculation using enthalpy and entropy change of chemical reaction, this paper showed that if the volume concentration of carbon dioxide in the air was floated up and down 20% from the literature value 0.03%, the decomposition temperatures of sodium carbonate were 1 227.69℃ and 1 203.74℃ respectively, which alcohol burner could not achieve, and the decomposition temperatures of sodium bicarbonate were 54.56℃ and 50.9℃ respectively, which alcohol burner was easy to achieve, so alcohol burner could only made sodium bicarbonate decompose to produce carbon dioxide, but not sodium carbonate.