The eggshell reaction in vinegar is an acid-base reaction. When you soak an egg in vinegar, the shell dissolves, but the interior semi-permeable membrane remains intact. Vinegar (acid) dissolves the eggshell's solid calcium carbonate crystals (base) into calcium and carbonate components. The vinegar's acidic environment prevents other substances from reacting with the egg's surface.
When you add an alkali to an acid, they react to form a salt and water. In this case, the acid is vinegar and the alkali is soda (sodium carbonate). The sodium carbonate reacts with the vinegar to create sodium acetate and carbon dioxide gas. Carbon dioxide is not visible, but it is out there occupying space inside the bottle. Sodium acetate is very soluble in water so it will be washed away when you wash the dishes after eating an egg soaked in vinegar.
If you leave the egg in the vinegar overnight or for several days, the vinegar will continue to dissolve more of the shell until all that is left is a white internal membrane. This is called "scrambled" egg because it contains no solid pieces of shell.
Eggs have been used as food and medicine for thousands of years. They are one of the most common animal products consumed worldwide. About 95 percent of eggs are eaten as food, while the remaining 5 percent are used in scientific research studies and medical treatments.
Vinegar is a kind of acid. Calcium carbonate is the main component of eggshells. Soaking an egg in vinegar causes the eggshell to absorb the acid and break down, or dissolve. The calcium carbonate will decompose into carbon dioxide gas, which will be released into the atmosphere. The gas can be absorbed by other substances such as plants, so the plant material will contain more of this element than normal. This is why fertilizers containing calcium carbonate produce stronger plants that require less phosphorus when grown in soil with low phosphorus levels.
The calcium carbonate in eggshells is used as a natural fertilizer. When placed in the garden, the shell will release its carbon content into the soil and act as a source of nitrogen for the vegetables. Because vinegar is a strong acid, only liquid eggshells should be used; do not use dry ones because they will not decompose.
You can use discarded eggshells as a natural fertilizer for your garden. However, avoid using old or rotten eggs as they may contain bacteria or chemicals that could harm your plants.
When vinegar (acetic acid) combines with eggshell (calcium carbonate), a water-soluble chemical, calcium acetate, and carbon dioxide gas are produced (the bubbles on the eggshell). This reaction occurs when any alcohol is added to an egg. The vinegar breaks down some of the calcium in the shell into soluble forms that can be removed from the egg.
The process of removing the calcium carbonate from the eggshell to produce calcium carbonate for use as a fertilizer involves chemicals and energy input. However, egg production by chickens provides a natural source of calcium carbonate for their bodies, so there is no need to remove it further. A chicken will use this material to build her own bones and teeth if she cannot find other sources of calcium.
People have used the shells from eggs to make tools over thousands of years. They did this by removing the calcium carbonate from the shell and mixing it with another substance - such as wood or stone - to form a solid material. The Greeks and Romans made knives out of the shells of fresh eggs. In modern times, people still use eggs as a source of calcium because it's easy to do and does not involve any risk involved with other methods such as mining or boiling away the soil around plants to get to their roots.