Question 1.5 - Chemistry: Molecular Nature Of Matter And Change

Question

Define physical change and chemical change. State which type of change occurs in each of the following statements: (a) Passing an electric current through molten magnesium chloride yields molten magnesium and gaseous chlorine. (b) The iron in discarded automobiles slowly forms reddish brown, crumbly rust.

Step-by-Step Solution

Answer

Answer

1. Passing an electric current through molten magnesium chloride yields molten magnesium and gaseous chlorine –Chemical Change.
2. The iron in discarded automobiles slowly forms reddish-brown, crumbly rust – Chemical change.

Definition

The change in which there is no formation of new bonds is termed a physical change. There is only a change in the physical property where there is no change in composition.

The change in the creation of new compounds is termed a chemical change.

Type of change

1. In example 1, magnesium chloride releases an electric current to get molten magnesium and gaseous chloride. Here, there is an occurrence of bond breakage between chloride and magnesium ions. There is a change in the chemical reaction.
2. In example 2, there is a formation of the reddish crust by iron on cars. The formation of the reddish crust happens by iron corrosion. The formed new compound is iron oxide. This is a chemical reaction.