Final answer:
The formation of a gas in a chemical reaction due to ions exchanging partners typically indicates that the reaction is a double-displacement or double-displacement reaction.
Step-by-step explanation:
The formation of a gas in a chemical reaction, due to ions changing places, often indicates that the reaction is a double-displacement reaction. A double-displacement reaction involves two ionic compounds in aqueous solution where the anions and cations exchange partners, resulting in the formation of two new compounds. This type of reaction typically occurs in aqueous solutions and one of the new compounds formed is often a solid precipitate, a gas, or a molecular compound such as water.
Examples of double-replacement reactions include reactions where an acid reacts with a base to form a salt and water (neutralization), or when two soluble salts react and produce an insoluble salt precipitate or a gas. Overall, the distinguishing characteristic of a double-displacement reaction is that both reactants are compounds and they swap their anion or cation partners.