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How should the reaction between vinegar and baking soda be classified?

What kind of a chemical reaction occurs when acetic acid (vinegar) and sodium bicarbonate (baking soda) are mixed- combination, decomposition, displacement, or double displacement?
Melissa Mattes 1/13/99

A double displacement reaction (also called a double decomposition or metathesis reaction) has the form

AB + CD rightarrow AC + BD

where A, B, C, and D are atoms or ions. The reaction between vinegar and baking soda can be written as a double displacement reaction if carbonic acid (H2CO3) is considered a product:

HC2H3O2(aq) + NaHCO3(aq) rightarrow NaC2H3O2(aq) + H2CO3(aq)

Here A, B, C, and D are H+, C2H3O2-, Na+, and HCO3-, respectively. [1, 2]

However, carbonic acid readily decomposes into carbon dioxide and water,

H2CO3(aq) doublearrow CO2(aq) + H2O(ell)

and the carbon dioxide can escape from the solution as a gas.

The combined equation is

HC2H3O2(aq) + NaHCO3(aq) rightarrow NaC2H3O2(aq) + H2O(ell) + CO2(g)

which doesn't fit neatly into one category, since it is a double displacement followed by a decomposition. When you encounter a reaction that is difficult to classify, consider the possibility that it may be the net or total equation for a sequence of steps.


  1. For double displacement reactions in aqueous solution, there is an additional requirement: if all of the products are soluble, strong electrolytes, then no reaction occurs. H2CO3 is a weak acid and so, a weak electrolyte. You can see the reason for this additional requirement when you try to write the net ionic equation for a reaction that involves only strong electrolytes: all of the ions are spectator ions in that case, and there is no net ionic equation.
  2. The reaction can also be classified as a neutralization since a hydrogen ion is donated by one reactant and accepted by another. Back

Author: Fred Senese senese@antoine.frostburg.edu

General Chemistry Online! How should the reaction between vinegar and baking soda be classified?

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Last Revised 08/17/15.URL: http://antoine.frostburg.edu/chem/senese/101/reactions/faq/classify-vinegar-bakingsoda.shtml