Chapter 2.2, Problem 4RQ

(a)

Interpretation Introduction

Interpretation: Whether the given statement is a chemical change or physical change needs to be explained.

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 4RQ

The given statement,food coloring is added to water, and the water appears red, will be categorized in a physical change.

Explanation of Solution

In any changes, if the composition remains the same then it is considered as an example of physical change. When any type of food color is added to water, it forms a mixture and mixture is a physical combination of two or more substances. Also, in this process, no new substance is formed. So, given statement 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, given statement is not categorized in a chemical change.

(b)

Interpretation Introduction

Interpretation: Whether the given statement is a chemical change or physical change needs to be explained.

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 4RQ

The given statement,an egg is placed in boiling water until the egg becomes hard-boiled, will be categorized in a chemical change.

Explanation of Solution

In a chemical change, important point is the formation of a new substance. An egg consists of a large amount of protein & amino acids. After boiling an egg, the heat will change its viscosity and also, it will chemically alter the egg's shape & chemical composition. So, given statement is a chemical change.

The given example is irreversible process. So, given statement is not categorized in a physical change.

(c)

Interpretation Introduction

Interpretation: Whether the given statement is a chemical change or physical change needs to be explained.

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 4RQ

The given statement, gasoline undergoes combustion in an automobile, will be categorized in a chemical change.

Explanation of Solution

In a chemical change, important point is the formation of a new substance. Combustion, start with carbon & oxygen and end up with carbon dioxide. The given statement is a chemical change as combustion gives rise to new products.

The given example is irreversible process. So, given statement is not categorized in a physical change.

(d)

Interpretation Introduction

Interpretation: Whether the given statement is a chemical change or physical change needs to be explained.

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 4RQ

The given statement, sugar is dissolved in a glass of iced tea, will be categorized in a physical change.

Explanation of Solution

In any changes, if the composition remains the same then it is considered as an example of physical change. When sugar dissolves in a glass of iced tea, no new product will be formed. So, given statement 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, given statement is not categorized in a chemical change.

(e)

Interpretation Introduction

Interpretation: Whether the given statement is a chemical change or physical change needs to be explained.

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 4RQ

The given statement, you inhale oxygen and exhale carbon dioxide, will be categorized in a chemical change.

Explanation of Solution

In a chemical change, important point is the formation of a new substance.

In this process, you inhale oxygen & exhale carbon dioxide, energy is produced in the mitochondria of cells and this process is irreversible. So, given statement is categorized in a physical change.

The given example is irreversible process. So, given statement is not categorized in a physical change.