Double Displacement Reactions: Gas Formation

Flashcards covering direct and indirect gas formation mechanisms in double displacement reactions.

No Reaction (in Solution)

The state when none of the expected reaction products are formed, leaving only individual ions floating in solution.

Direct Formation of a Gas

A process where an acid reacts with a sulfur-containing compound to produce hydrogen sulfide gas ($H_2S$), as in $2HCl(aq) + FeS \rightarrow FeCl_2(aq) + H_2S(g)$.

Indirect Formation of a Gas

A reaction where an acid reacts with a carbonate to produce water, carbon dioxide gas, and an ionic compound via an unstable intermediate across two steps.

Carbonic Acid ($H_2CO_3$)

An unstable intermediate formed when an acid reacts with a carbonate that quickly decomposes into water and carbon dioxide: $H_2CO_3(aq) \rightarrow H_2O(l) + CO_2(g)$.

Overall Reaction of $HCl$ and $CaCO_3$

The net chemical equation: $2HCl(aq) + CaCO_3(s) \rightarrow CaCl_2(aq) + H_2O(l) + CO_2(g)$.