Sodium bicarbonate (NaHCO3) can be decomposed by heating to produce sodium carbonate, water and carbon dioxide. This decomposition reaction at above 100 degrees Celsius can be written as:
2 NaHCO3 -> Na2CO3 + H2O (l) + CO2 (g)
In the reaction, 2 moles of sodium bicarbonate is used to produced 1 moles of Na2CO3. Carbon dioxide, CO2 is going to escape in the form of gas while water, H2O, will eventually evaporate which will make Na2CO3 the only compound remaining.
By stoichiometry, we can solve the relative amount of each compound produced. For example, 0.500 grams of NaHCO3 is used, by computation:
`0.500 grams NaHCO3 x (1 mol e NaHCO3)/(84 grams) x (1mol e Na2CO3)/(2 mol es NaHCO3)`
`x (106 grams)/(mol e Na2CO3) = 0.315 grams Na2CO3`
Relatively, if you measured 0.500 grams of NaHCO3, 0.315 grams of Na2CO3 will be produced. Of course in laboratory experiment it would be impossible to have an exact value of the product so we can have some values near 0.315 grams.