What Is the Chemical Formula for Baking Soda and Vinegar

Baking soda is sodium bicarbonate, with the chemical formula NaHCO₃. The reactive acid in vinegar is acetic acid, CH₃COOH. When they react, they form sodium acetate, water and carbon dioxide gas:

NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂

The bubbles are carbon dioxide escaping from the liquid. There is no single formula for “baking soda and vinegar” together: they are two substances that react, and vinegar itself is a mixture.

What the equation means

The equation shows that one mole of sodium bicarbonate reacts with one mole of acetic acid. The products are one mole each of sodium acetate, water and carbon dioxide. This is a 1:1 mole ratio, not a 1:1 ratio by spoonful or by mass.

The reaction is an acid-base reaction. Acetic acid transfers a hydrogen ion to the bicarbonate ion, HCO₃⁻, producing carbonic acid, H₂CO₃. Carbonic acid then breaks down into water and carbon dioxide. The gas forms bubbles and escapes from an open container.

The overall reaction stops producing gas when one of the reactants has been used up. If there is more baking soda than the available acetic acid can react with, some baking soda remains. If there is more acid, some remains in the liquid.

Vinegar is mostly water with acetic acid dissolved in it, so it does not have one chemical formula. Its exact concentration can vary. When people ask for vinegar’s formula in this reaction, they usually mean the formula of its reactive ingredient, CH₃COOH. Acetic acid is a weak acid Encyclopaedia Britannica: Acetic Acid.

Sodium bicarbonate, NaHCO₃, is a compound Encyclopaedia Britannica: Sodium Bicarbonate. It is also known as baking soda or, in some places, bicarb. It acts as a base in this reaction. PubChem describes sodium bicarbonate as a weak base, while PubChem’s acetic acid entry identifies the acid involved.

The equation is balanced: each type of atom appears in equal numbers on both sides. The sodium and acetate end up together in sodium acetate, while the bicarbonate carbon becomes carbon dioxide. The hydrogen and oxygen atoms are accounted for in the products, water and carbon dioxide. No atoms are created or lost.

One worked example

Suppose you have 84 grams of sodium bicarbonate and enough vinegar to provide excess acetic acid. Sodium bicarbonate has a molar mass of about 84 grams per mole, so this amount is about one mole.

According to the balanced equation, one mole of sodium bicarbonate reacts with one mole of acetic acid. It can produce one mole of carbon dioxide, with sodium acetate and water as the other products. One mole of carbon dioxide has a mass of about 44 grams. The actual amount of gas released can be lower if there is not enough acetic acid to react with all the baking soda.

This calculation uses moles, not equal spoonfuls. A spoonful of solid baking soda and a spoonful of vinegar do not contain matching amounts of the reacting compounds. Vinegar is a dilute solution, and its acetic acid concentration affects how much baking soda it can react with.

Factors that affect the fizz

The amount of carbon dioxide depends on how much of the limiting reactant is available. For instance, if the acetic acid runs out first, adding more baking soda will not produce more gas. The extra baking soda remains unreacted. If baking soda runs out first, adding more vinegar will not produce more gas from that batch.

Temperature and concentration can affect how quickly the reaction proceeds. Warmer or more concentrated vinegar may make bubbling occur faster, but the maximum amount of gas still depends on the quantities of acetic acid and sodium bicarbonate that react. The equation gives the chemical ratio; it does not mean every kitchen mixture will have the exact proportions needed for complete reaction.

In an open container, carbon dioxide escapes into the air. In a sealed container, the gas can build pressure. Do not seal a container while the reaction is producing gas.

Key Takeaways

• Baking soda is sodium bicarbonate, NaHCO₃. Vinegar’s reactive acid is acetic acid, CH₃COOH.
• The balanced reaction is NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂.
• The reaction produces sodium acetate, water and carbon dioxide. The fizz is carbon dioxide gas.
• Vinegar is a mixture of acetic acid and water, so it does not have one formula.
• The equation gives a 1:1 mole ratio. The reactant that runs out first limits how much carbon dioxide can form.