Chapter 17, Problem 48A

(a)

Interpretation Introduction

Interpretation:

The process is to classified as exothermic or endothermic.

Concept Introduction:

Reactions that absorb heat are referred to as endothermic reactions. The enthalpy change for the endothermic reaction is positive.

Reactions that release heat are known as exothermic reactions. The enthalpy change for the endothermic reaction is negative.

Answer to Problem 48A

Condensing steam is an exothermic process.

Explanation of Solution

Condensation is the change of state of matter from a gaseous state to a liquid state.

The energy must be released by the gas to convert into a less random state called a liquid state. Thus, condensation is an exothermic process.

(b)

Interpretation Introduction

Interpretation:

The process is to classified as exothermic or endothermic.

Concept Introduction:

Reactions that absorb heat are referred to as endothermic reactions. The enthalpy change for the endothermic reaction is positive.

Reactions that release heat are known as exothermic reactions. The enthalpy change for the endothermic reaction is negative.

Answer to Problem 48A

Evaporating alcohol is an endothermic process.

Explanation of Solution

Evaporation is the change of state of matter from the liquid state to the gaseous state.

The energy must be absorbed by the liquid molecules to break the intermolecular forces and convert them into a more random gaseous state.

(c)

Interpretation Introduction

Interpretation:

The process is to classified as exothermic or endothermic.

Concept Introduction: Reactions that absorb heat are referred to as endothermic reactions. The enthalpy change for the endothermic reaction is positive.

Reactions that release heat are known as exothermic reactions. The enthalpy change for the endothermic reaction is negative.

Answer to Problem 48A

Burning of alcohol is an exothermic process.

Explanation of Solution

Burning of alcohol is a combustion reaction where alcohol reacts in the presence of oxygen to liberate heat. Thus, it is an exothermic process:

(d)

Interpretation Introduction

Interpretation:

The process is to classified as exothermic or endothermic.

Concept Introduction:

Reactions that absorb heat are referred to as endothermic reactions. The enthalpy change for the endothermic reaction is positive.

Reactions that release heat are known as exothermic reactions. The enthalpy change for the endothermic reaction is negative.

Answer to Problem 48A

The baking of potatoes is an endothermic process.

Explanation of Solution

Baking of potato involves the absorption of heat from the oven to cook the potato and thus, baking of potato is an endothermic process.