The solution contains HCl (hydrochloric acid). When the solution (HCl) reacts with crushed eggshells, which are primarily made of calcium carbonate (CaCO3), it produces carbon dioxide gas (CO2). This CO2 gas turns lime water milky due to the formation of calcium carbonate precipitate. The chemical reaction is:
CaCO3+2HCl→CaCl2+H2O+CO2↑\text{CaCO}_3+2\text{HCl}\rightarrow \text{CaCl}_2+\text{H}_2\text{O}+\text{CO}_2\uparrow CaCO3+2HCl→CaCl2+H2O+CO2↑
The carbon dioxide gas produced reacts with lime water (Ca(OH)2) to form calcium carbonate, which causes the milky appearance:
Ca(OH)2+CO2→CaCO3+H2O\text{Ca(OH)}_2+\text{CO}_2\rightarrow \text{CaCO}_3+\text{H}_2\text{O}Ca(OH)2+CO2→CaCO3+H2O
This confirms the solution contains hydrochloric acid (HCl).
