Name: Reactions of Metal Carbonates with Acids
Uploaded: 2019-07-19
Duration: 4 min 6 s
Description: When substances like metals and liquids like acid react, it produces salt, water, and carbon dioxide. Here, in this video, it has been explained in detail wi...

Question

A metal X reacts with dilute

HCl

to produce effervescence. The gas evolved extinguishes a burning candle and turns lime water milky. Identify the gas evolved. If excess gas is passed through lime water, milkiness disappears, the solution becomes clear and forms compound Y. Identify X and Y. Give your answer with a balanced chemical equation.

Accepted Answer

When dilute hydrochloric acid reacts with sodium hydrogen carbonate then sodium chloride, carbon dioxide and water are formed:

${NaHCO}_{3} (s) + HCl (aq) \to NaCl (aq) + {CO}_{2} (g) + H_{2} O (l)$

Thus, the acid reacts with carbonates and hydrogen carbonates to evolve carbon dioxide gas. This carbon dioxide gas reacts with lime water as follows:

The metal compound X is sodium hydrogen carbonate.

(a) When carbon dioxide gas is passed through lime water the lime water turns milky due to the formation of a white precipitate of calcium carbonate:

$Ca {(OH)}_{2} (aq) + {CO}_{2} (g) \to {CaCO}_{3} (s) + H_{2} O (l)$

(b) If the excess of carbon dioxide gas is passed through lime water then the white precipitate formed first dissolves due to the formation of a soluble salt calcium hydrogen carbonate and the solution becomes clear again.

${CaCO}_{3} (s) + {CO}_{2} (g) + H_{2} O (l) \to Ca {({HCO}_{3})}_{2} (aq)$

The metal compound Y is calcium hydrogen carbonate.

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