What will happen to eggshell soaked in baking soda and water?

When eggshell is soaked in baking soda and water, a chemical reaction will take place between the eggshell (calcium carbonate) and baking soda (sodium bicarbonate). The reaction can be represented as follows:

CaCO3 (calcium carbonate) + 2NaHCO3 (sodium bicarbonate) → CO2 (carbon dioxide) + H2O (water) + Ca(HCO3)2 (calcium bicarbonate)

The reaction produces carbon dioxide gas which causes bubbles to form on the eggshell. The calcium carbonate in the eggshell dissolves in the water, and the carbon dioxide gas escapes from the solution. Calcium bicarbonate is also formed as a product of the reaction.

This reaction is a simple example of an acid-base reaction, where the baking soda acts as the base and the eggshell as the acid. The reaction is exothermic, meaning that it releases heat.