The Vinegar and Baking Soda Reaction Equation Explained

The balanced equation for baking soda reacting with vinegar is:

NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂

Sodium bicarbonate (NaHCO₃), the chemical name for baking soda, reacts with acetic acid (CH₃COOH), the acid in vinegar. The products are sodium acetate (CH₃COONa), water (H₂O), and carbon dioxide gas (CO₂). The bubbles and foam are carbon dioxide escaping from the liquid.

Vinegar is a solution of acetic acid in water. Acetic acid gives vinegar its sour taste (Encyclopaedia Britannica). The equation shows the reaction between the acid and bicarbonate; it does not include the water already present in vinegar.

How the reaction works

Baking soda contains sodium ions (Na⁺) and bicarbonate ions (HCO₃⁻). Acetic acid can transfer a hydrogen ion (H⁺) to bicarbonate. This forms carbonic acid (H₂CO₃), which breaks down into water and carbon dioxide:

H⁺ + HCO₃⁻ → H₂CO₃ → H₂O + CO₂

The sodium ion pairs with acetate left behind by the acetic acid, forming sodium acetate. Carbon dioxide can dissolve in the liquid for a time, but some escapes as bubbles.

The equation is balanced: each side has 3 carbon atoms, 5 hydrogen atoms, 5 oxygen atoms, and 1 sodium atom. The atoms are rearranged into different substances.

The full equation uses formulas for the compounds as written in the mixture. A simplified net ionic equation shows the part that produces the gas:

HCO₃⁻ + H⁺ → H₂O + CO₂

In a dilute aqueous mixture, sodium and acetate are present predominantly as dissolved ions, so the net ionic equation leaves them out. Both equations describe the same reaction at different levels of detail.

What the equation tells you

The coefficients are all 1. One formula unit of sodium bicarbonate reacts with one molecule of acetic acid to produce one formula unit of sodium acetate, one molecule of water, and one molecule of carbon dioxide. In mole terms, the ratio is also 1:1:1:1:1.

The reaction stops producing carbon dioxide when one of the reactants has been used up. That reactant is called the limiting reactant. Adding more of the other ingredient after that point will not produce more carbon dioxide unless more of the limiting reactant is added.

Sodium acetate stays dissolved in the liquid under ordinary mixing conditions. It is a salt made from sodium ions and acetate ions. Carbon dioxide is the gas that escapes. PubChem describes sodium bicarbonate as a compound that can release carbon dioxide during decomposition; the vinegar reaction follows the acid-bicarbonate pathway described above (PubChem).

One example: estimating the carbon dioxide produced

Suppose you mix 14 g of baking soda with enough vinegar to react with all of it. This is an example calculation, not a recommended household measurement.

The molar mass of sodium bicarbonate is about 84 g/mol. Dividing the mass by the molar mass gives:

14 g ÷ 84 g/mol ≈ 0.17 mol NaHCO₃

Because the equation has a 1:1 ratio between sodium bicarbonate and carbon dioxide, the maximum theoretical yield is about 0.17 mol CO₂, provided there is enough acetic acid. If there is less acid than required, the actual yield will be lower.

This calculation gives an amount of gas in moles, not a fixed volume. The volume depends on conditions such as temperature and pressure, and some carbon dioxide may remain dissolved in the liquid. Household vinegar also varies in its acetic acid concentration, so the equation alone cannot tell you how much vinegar is needed for a particular batch.

What to expect when mixing them

The reaction usually produces visible fizzing as carbon dioxide leaves the liquid. The amount and duration depend on how much of each ingredient is present and how concentrated the vinegar is. If the mixture is open to the air, the gas can escape. In a closed container, carbon dioxide can build pressure. Do not use a rigid, sealed container for this reaction.

Key Takeaways

• The balanced equation is NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂.
• Baking soda is sodium bicarbonate, and the acid in vinegar is acetic acid.
• The visible fizz comes from carbon dioxide escaping from the liquid.
• The equation gives a 1:1 mole ratio between sodium bicarbonate, acetic acid, and carbon dioxide.
• The amount of gas is limited by whichever reactant runs out first.