Question

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

Answer 1

Explanation:

A chemical reaction is defined as a reaction which leads to change in chemical composition of a substance.

During a chemical change there might be evolution of gas which is an indication that composition of reactants has been changed.

For example, precipitation, combustion etc causes chemical changes.

   $Zn + 2HCl \rightarrow ZnCl_{2} + H_{2}$

On the other hand, a change which does not cause any change in chemical composition of the substance is known as a physical change.

For example, size, volume, mass etc are physical changes.

Thus, we can conclude that formation of a gas in a chemical reaction, due to ions changing places, often indicates that the reaction is chemical change.

Answer 2

A single-displacement reaction, also known as asingle-replacement reaction, is a type of chemicalreaction where an element reacts with a compound and takes the place of another element in that compound. This type of reaction is typically pictured like this: Here, A replaces B in the compound BC.