Re: When flour is added to vinegar, why doesn't it fuzz or bubble?

Hi Emma,

The reason vinegar reacts with baking soda is because vinegar is a medium- strength acid (acetic acid or CH3COOH) and baking soda (sodium bicarbonate or NaHCO3) is a weak base. When an acid is mixed with a base, a reaction will occur. In this case:

CH3COOH + NaHCO3 ---> CH3COONa + H2CO3 (carbonic acid)
Carbonic acid quickly decomposes into carbon dioxide and water:
H2CO3 ---> H2O + CO2
The CO2 is what you see foaming and bubbling in this reaction.

Flour, on the other hand, is made up of a number of different compounds, including starch (~80%), protein (~13%), ash (~0.5%) and dietary fibre (~3.5%). Most of these ingredients are not terribly reactive to acids.

To find out more about acid/base reactions, go to Acids, Bases and pH Scale or An Introduction to Acids and Bases. They have some really good information to help explain why acids and bases react.

BTW, it is not a good idea to mix just any chemicals you find around the house. You could seriously harm yourself if you don’t know know what to expect.

Thanks for your question!

Kieran