At nearly 70°C, sodium bicarbonate shows the property of gradually decomposing, which makes it usable in bakery products. The product of decomposition responsible for this use of sodium bicarbonate is

Sodium bicarbonate (NaHCO3), commonly known as baking soda, undergoes thermal decomposition when heated. This process begins gradually at temperatures above 50°C and becomes significant around 70°C to 80°C [1]. The chemical reaction for this thermal decomposition is 2 NaHCO3 → Na2CO3 + H2O + CO2. The primary product responsible for its use in the bakery industry is carbon dioxide (CO2) gas [1]. As the gas is released within the dough or batter, it creates bubbles that cause the bread or cake to rise, resulting in a soft and spongy texture [1]. While water vapor is also a byproduct of this decomposition, it is the expansion of carbon dioxide that provides the essential leavening action required for fluffy baked goods [1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Uses of Baking soda > p. 31