Q28 E - Chemistry (OpenStax)

Question

Classify each of the following changes as physical or chemical: 

(a) coal burning 

(b) ice melting 

(c) mixing chocolate syrup with milk 

(d) explosion of a firecracker 

(e) magnetizing of a screwdriver

Step-by-Step Solution

Answer

1. Chemical
2. Physical
3. Physical
4. Chemical
5. Physical

Understanding what is physical and chemical change

Physical change is a type of change in which physical structure changes but chemical composition does not change.

Chemical change is a change in which chemical composition of a substance changes.

Analyzing each phenomenon individually

1. Coal burns in air which effects its chemical composition which cannot be reversed. So, it is chemical change.
2. It is a physical change as its chemical composition does not change,
3. Chemical composition is not changed, so it is a physical change.
4. Elements used in firecrackers reacts with oxygen and its chemical composition changes. So, it is a chemical change.
5. It is a physical change as chemical composition is not changed.