What is the chemical reaction between baking soda and vinegar?

Need a fun experiment for kids to do in science class? Have them combine baking soda and vinegar and see what happens. The ingredients in this experiment are safe and are found in most households, and when they combine, they produce a reaction that pretty dramatic.

In fact, baking soda and vinegar are combined to make the effects for paper mache volcanoes because one of the final products in the reaction, carbon dioxide, is heavier than air, and although it is a gas, when it is released in heavy concentrations it looks like white lava when it flows out of the volcano. (If you’ve ever seen the smoke from dry ice, this is the same reaction/result.)

But what underlies the reactivity of baking soda and vinegar to one another?

Vinegar is impure, diluted acetic acid. It has a chemical formula of C2H4O2. (Acetic acid is a weak acid, because it only gives up one H+ (hydroxide) ion when mixed with an aqueous solution.) Baking soda, also known as bicarbonate of soda or sodium bicarbonate, is a base. It’s chemical formula is NaHCO3.

Acids and bases are highly reactive to each other because when they are combined with water, acids release H+ hydrogen ions and bases release OH- hyodroxide ions. When acids and bases are combined together, the released hydrogen and hydroxide ions join to form H2O water molecules.

One of the reasons these reactions are useful is that acids are corrosive, and bases are commonly used to neutralize them (producing water and a salt in the reactions as seen below) in process that continues until equalization is reached — that is, until either all of the loose H+ ions and/or all of the -OH ions have combined with each other. Whichever one of these ions is left over in the solution will determine the resulting pH of the solution. (On the pH scale of 0 to 14, neutral is 7, anything below 7 is an acid, and anything above 7 is a base.)

The reaction.

A chemical reaction is defined as a transformation resulting in a change of composition, constitution and/or configuration of a compound. There are six types of chemical reactions — combustion, synthesis, single displacement, double displacement, decomposition, and acid/base.

The combination of vinegar and baking soda results in what is known as a multi-step reaction. What looks like one reaction is actually two. The reaction between vinegar and baking soda is an acid/base reaction, followed by a decomposition reaction.

The first is an acid/base reaction.

C2H4O2 + NaHCO3 –> NaC2H3O2 + H2CO3

The precipitate of this reaction is sodium acetate, which is an inorganic, non-water ionic

product commonly referred to as a salt.

The second reaction is a release of carbon dioxide in what is known as a decomposition reaction. H2CO3 is carbonic acid. This molecule is unstable, and it immediately dissolves into carbon dioxide and water.

H2co3 –> H2o + Co2

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