CBSE Class 7 Answered

We know that baking soda contains sodium hydrogen carbonate and household vinegar contains acetic acid.

Take baking soda (sodium hydrogen carbonate) in one test tube and vinegar (acetic acid) in another test tube.

When baking soda is treated with an acid like vinegar, a brisk effervescence is observed.

Can you guess what has happened in the reaction and which gas is evolved in the reaction?

Metal carbonates and hydrogen carbonates react with acids to give salt, carbon dioxide and water.

Acid + metal carbonate/Metal hydrogen carbonate →Salt+Carbon dioxide + water

So , Acetic acid reacts with sodium hydrogen carbonate to release carbon dioxide gas , sodium acetate and water.

CH₃COOH + NaHCO₃ →CH₃COONa + CO₂ + H₂O

Similarly, zinc carbonate on reacting with sulphuric acid produces zinc sulphate, water and carbon dioxide.

ZnCO₃ + H₂SO₄ → ZnSO₄ + CO₂ + H₂O