Question

The formation of a gas in a chemical reaction, due to ions changing places, often indicates that the reaction is which type?
A) synthesis

B) double-displacement

C) decomposition

D) single-displacement

Answer 1

Answer: The correct answer is D.

Explanation: In a chemical reaction, when there is changing of ions taking place and is leading to the formation of a gas can be considered as a single displacement reaction.

Single-Displacement reactions are defined as the reactions in which a higher reactive metal displaces a lower reactive metal. This is in reference to the reactivity series.

Hydrogen lies below in the reactivity series and when the higher reactive metal displaces hydrogen from a chemical reaction, it leads to the formation of hydrogen gas.

Example:

$Zn^{2+}+2HCl\rightarrow ZnCl_2+H_2(g)$