Q1.
Aman accidentally spilt vinegar on some pieces of an eggshell or marble and noticed bubbling. He then poured a soap solution on another piece of eggshell or marble, but no bubbles appeared. Why did bubbles occur with vinegar but not with soap solution?
Answer
Because eggshell and marble are made of the same substance — calcium carbonate — and calcium carbonate reacts with an acid, not with a base.
Eggshell / marble = calcium carbonate
Vinegar = an acid (acetic acid)
Acid + carbonate → salt + water + carbon dioxide gas
→ the gas escapes as the bubbles Aman saw
Vinegar = an acid (acetic acid)
Acid + carbonate → salt + water + carbon dioxide gas
→ the gas escapes as the bubbles Aman saw
Soap solution is basic. A base does not react with calcium carbonate in this way, so no gas is produced and no bubbles appear.
Why it happens: the bubbling is not the acid "dissolving" the shell in a general way — it is a specific reaction that releases carbon dioxide. The bubbles are therefore a quick field test: drop vinegar or lemon juice on a stone, and if it fizzes, the stone contains carbonate.
Did you know? This is exactly why marble monuments are damaged by acid rain, and why the marble floors of a temple should never be cleaned with lemon or vinegar. It is also why chalk (also calcium carbonate) fizzes in dilute acid in the laboratory.