Chapter 3.2, Problem 10SSC

Interpretation Introduction

Interpretation:

Whether crushing an aluminum can is a chemical change or physical change needs to be determined.

Concept introduction:

The nature of any substance is explained by their chemical properties and physical properties.

A physical property describes the physical changes of a substance. Physical change is a temporary change; it is a reversible change. For example, color, mass, volume, etc.

A chemical property describes how a substance reacts with other substances. In a chemical change, a new substance is formed and absorption of energy or loss of energy occurs; it is an irreversible change. For example, rusting, dissolving, etc.

Answer to Problem 10SSC

Crushing an aluminum can is an example of physical change.

Explanation of Solution

In any changes if the composition remains the same then it is an example of physical change. The aluminum can is divided into two parts or more than two parts but the material is the same in both parts. In this process, no new substance is formed. So, it is considered as a physical change.

In a chemical change, important point is the formation of a new substance; in the given example, no new substance is formed. So, it is not considered in a chemical change.

Interpretation Introduction

(b)

Interpretation:

Whether recycling used aluminum cans to make new aluminum cans is a chemical change or physical change.

Concept introduction:

The nature of any substance is explained by their chemical properties and physical properties.

A physical property describes the physical changes of a substance. Physical change is a temporary change; it is a reversible change. For example, color, mass, volume, etc.

A chemical property describes how a substance reacts with other substances. In a chemical change, a new substance is formed and absorption of energy or loss of energy occurs; it is an irreversible change. For example, rusting, dissolving, etc.

Answer to Problem 10SSC

The recycling used aluminum cans to make new aluminum cans is a physical change.

Explanation of Solution

In this process, the composition remains the same as in a liquid-state and in solid-state. The liquid changes into solid when the intermolecular space is decreased and the arrangement of molecules got fixed. Molecules formof solid is a complex structure. The melting of aluminum cans without loss of the physical property and also, formation of new aluminum cans. So, it is considered as physical change.

In a chemical change, important point is the formation of a new substance; in the given example, no new substance is formed. So, it is not considered in a chemical change.

Interpretation Introduction

(c)

Interpretation:

Whether aluminum combining with oxygen to form aluminum oxide is a physical or chemical change.

Concept introduction:

The nature of any substance is explained by their chemical properties and physical properties.

A physical property describes the physical changes of a substance. Physical change is a temporary change; it is a reversible change. For example, color, mass, volume, etc.

A chemical property describes how a substance reacts with other substances. In a chemical change, a new substance is formed and absorption of energy or loss of energy occurs; it is an irreversible change. For example, rusting, dissolving, etc.

Answer to Problem 10SSC

A chemical reaction between aluminum and oxygen to form aluminum oxide is a chemical change.

Explanation of Solution

In a chemical reaction the property of the product is different from the reactant and their composition is different from the original reactant. So, it is considered a chemical change. Chemical change is an irreversible process.

The statement in the given question is an irreversible process. So, it is not considered as physical change.