Sodium Bicarbonate (Baking Soda) (NaHCO₃) — Properties, Uses & Safety

Overview

Sodium bicarbonate (NaHCO3), universally known as baking soda, is a white crystalline solid with a molar mass of 84.01 g/mol and a slightly salty, alkaline taste. It is an ionic compound consisting of sodium cations (Na⁺) and bicarbonate anions (HCO3⁻). Sodium bicarbonate is mildly basic in aqueous solution, with a pH of about 8.3, making it useful as an antacid to neutralize excess stomach acid (HCl). In nature, sodium bicarbonate is found as the mineral nahcolite and in the waters of mineral springs. It is manufactured industrially by the Solvay process, which reacts sodium chloride, ammonia, and carbon dioxide. Baking soda is one of the most versatile household chemicals. In baking, it acts as a leavening agent: when combined with an acid (such as vinegar, lemon juice, or cream of tartar), it produces carbon dioxide gas (NaHCO3 + acid → salt + H2O + CO2), which causes dough and batter to rise. When heated above 80 °C, sodium bicarbonate decomposes on its own (2 NaHCO3 → Na2CO3 + H2O + CO2), which is why it works in recipes even without an added acid. Beyond baking, sodium bicarbonate is used as a gentle abrasive cleaner, deodorizer, fire extinguisher component (in dry chemical extinguishers), water treatment agent, and in personal care products like toothpaste. Medically, it serves as an antacid and is used intravenously to treat metabolic acidosis. Sodium bicarbonate has no significant GHS hazards and is generally recognized as safe (GRAS) by the FDA. For chemistry students, sodium bicarbonate is a treasure trove of learning opportunities. The baking soda and vinegar reaction is one of the most iconic chemistry demonstrations, illustrating acid-base reactions, gas production, and stoichiometry. Its thermal decomposition demonstrates endothermic reactions. The bicarbonate ion itself is amphoteric — it can act as both an acid and a base — making it an excellent example for teaching about amphoterism and buffer systems. Sodium bicarbonate connects everyday kitchen science to fundamental chemistry principles, making it an ideal compound for engaging students who are new to the subject.

IUPAC Name

sodium hydrogen carbonate

CAS Number

144-55-8

PubChem CID

516892

Molecular Formula

NaHCO₃

Molar Mass

84.01 g/mol

State at STP

solid

Appearance

White crystalline powder

Physical Properties

Melting Point

50 °C

Density

2.2 g/cm³

Solubility in Water

96 g/L at 25 °C

ΔH°f

-950.8 kJ/mol

Composition