Sodium Bicarbonate
Properties
| State | Solid (white crystalline powder) |
| Color | White |
| Solubility | Soluble in water (96 g/L at 20 °C) |
| Melting Point | 50 °C (decomposes to Na2CO3 + H2O + CO2) |
| Boiling Point | Decomposes before boiling |
About Sodium Bicarbonate
Sodium bicarbonate is one of those compounds that earns its place in three completely different cabinets — the kitchen pantry, the medicine chest, and the laboratory acid spill kit. Formula NaHCO3, molar mass 84.007 g/mol, mildly alkaline solution (pH around 8.3 at saturation), and the clean trick that it decomposes to Na2CO3 + H2O + CO2 starting around 50 °C and finishing by 200 °C. That decomposition is exactly the chemistry that makes a quick bread rise: an acid in the batter (buttermilk lactic acid, lemon juice citric acid, vinegar acetic acid) protonates the bicarbonate, releasing CO2 bubbles trapped by gluten and starch as the loaf sets in the oven. Industrially, NaHCO3 is produced by the Solvay process from brine, ammonia, and limestone — about 2 million tonnes a year worldwide, much smaller than its big sibling Na2CO3 because anything destined for glass goes through soda ash directly. In the biochem lab, sodium bicarbonate is the buffer that maintains physiological pH 7.4 in cell culture media (paired with 5 percent CO2 in the incubator gas phase, the buffer equilibrium gives you exactly that pH).
Where you'll encounter it
If you've ever poured baking soda on a kitchen grease fire, neutralized a battery acid spill, brushed your teeth with a fluoride toothpaste, or sat in an emergency room while a nurse pushed a 50-mL amp of 8.4% NaHCO3 for tricyclic antidepressant overdose, you've met sodium bicarbonate doing four different jobs. In the cell culture room, every flask of DMEM or RPMI sits in a 37 °C incubator gassed to 5% CO2 specifically because the medium is buffered with about 2 g/L NaHCO3 — the carbonate-CO2 equilibrium pins pH at 7.4 only when the gas phase is right, and a flask left on the bench turns purple within 10 minutes as CO2 escapes and pH drifts up. Competitive cyclists used to sodium-bicarbonate-load before time trials to buffer lactic acid and squeeze a few seconds out of a 4-minute pursuit. Climbers' chalk bags are pure magnesium carbonate, but the same principle applies — moisture-absorbing alkaline carbonate.
Common Uses
- CO2-generating leavening agent in quick breads, biscuits, pancakes
- Acid-spill neutralizer in laboratory and industrial first-response kits
- Bicarbonate buffer (~24 mM) in cell culture media at 5% CO2 incubator gas
- IV treatment of tricyclic antidepressant overdose and metabolic acidosis
- Antacid for occasional heartburn (sold OTC as Alka-Seltzer)
- Fire suppressant in BC-class dry chemical extinguishers for grease fires
- Mild abrasive in toothpaste and household scouring formulations
- Hemodialysis dialysate component for bicarbonate replacement therapy
Safety Information
GRAS for food and pharmaceutical use (FDA 21 CFR 184.1736). GHS: not classified — no H-codes assigned. OSHA has not set a PEL. The risks are quantitative not qualitative: chronic ingestion of large quantities causes metabolic alkalosis (tetany, muscle cramps, arrhythmias), and a single oral teaspoon-and-vinegar treatment for indigestion has on rare occasion ruptured stomachs from acute CO2 generation. Sodium load matters for hypertensive and CHF patients — one teaspoon delivers about 1.3 g sodium. Powder mildly drying to skin on prolonged contact. Decomposition at temperatures above 50 °C releases CO2, which can pressurize sealed containers. Standard food-handling PPE is sufficient.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.