Vinegar is made of mainly acetic acid and water.
More Info: Vinegar is created through a fermentation process. Anything that contains sugar and starch can be made into vinegar, but some things make better vinegar than others. The sugar in a substance is converted into an alcohol which is then converted into acetic acid.
When making a fruit based vinegar, wild yeast is added to help convert the sugar into alcohol.
Vinegar can also be made of things that are starch based instead of sugar based, and it can be made out of some herbs. When starch based vinegar is made, the starch must first be converted into sugar. The rest of the process is the same as the fruit vinegar process. The amount of sugar or starch in a product determines how strong the end product will be.
The first part of the vinegar making process is anaerobic, meaning it happens in an environment where there is no oxygen. This part takes up to six weeks. The second part of the process requires oxygen. A mother culture can be added to this step to speed up the process, but is not required. This step takes up to nine months.
Fun Experiment: For a fun science experiment, add vinegar to baking soda. This causes a chemical reaction with an end product of carbon dioxide. Vinegar will also dissolve pearls and soften egg shells.