Question

What happens when nitric acid is added to the egg shell?

Answer 1

Egg shell contains calcium carbonate. On reaction with nitric acid the calcium carbonate forms calcium nitrate along with carbon-dioxide gas and water. It leads to the formation of bubbles on the surface of the egg shell. The chemical formula of nitric acid is $H N{{O}_{3}}$.

Complete step by step answer:
The calcium carbonate crystals present in the egg shell breaks into calcium and carbonate ions reacting with nitric acid. The calcium ions form the calcium nitrate and the carbonate ions form carbon-dioxide and water. The reaction is given as-
$Ca C{{O}_{3}}+2HN{{O}_{3}}\to Ca{{(N{{O}_{3}})}_{2}}+C{{O}_{2}}+{{H}_{2}}O$
The carbon-dioxide formed has the property of turning lime water milky.
Eggshell can also be dissolved using other acids rather than nitric acid. The action of acetic acid also has a similar kind of effect on eggshell as that seen with nitric acid. The bubbles due to carbon-dioxide are formed immediately around the egg when it is dipped in acetic acid, leaving the eggshell for more than 24 hours in acetic acid leads to the complete dissolving of calcium carbonate leaving the soft membrane behind. The egg is made bouncy and squishy by placing it in vinegar and covering it for a day or two.

Note:
The yellowish part of the egg is known as egg yolk. It is a rich source of proteins and lipids. The eggshell has around 17000 tiny pores and is completely made up of calcium carbonate. It acts as a semipermeable membrane which permits the passage of air and moisture through its pores. Little bit composition of eggshell can differ based on the fact that it relates to which bird.