Chapter 8, Problem 1IQ

Complete the following concept map that summarizes some of the key ideas about energy.

Summary Introduction

To complete: The concept map that summarizes some of the key ideas about energy.

Introduction: Thermodynamics is the study of energy and its transformation that drives all activities of the universe. The system that does not exchange energy with its surroundings is known as a closed system. The system that exchanges energy with its surroundings is known as an open system. There are two laws of thermodynamics, namely the first law and the second law.

Answer to Problem 1IQ

Pictorial representation: Fig.1 shows the concept map that summarizes some of the key ideas about energy.

Fig.1: Concept map that summarizes some of the key ideas about energy.

Explanation of Solution

Energy is necessary for all living organisms to carry out their life processes. Living cells obtain energy in different forms, and they also have the mechanisms to convert the energy from one form to different forms. Energy is defined as the capability to do work. When work is done, energy is transferred from one form to another form, or between systems. Energy is generally expressed in units of work that is kilojoules (kJ). Energy can also be expressed in units of heat energy that is kilocalories (kcal).

Potential energy and kinetic energy are the two forms of energy. Potential is the energy of position or stored energy such as the arrangement of electrons in bonds between atoms. Kinetic energy is the energy of motion such as light and heat. A person pulling an arrow back on a bow and holding a baseball in the backswing are examples of potential energy. When the bowstring pushes the arrow toward its target and throwing a baseball are examples of kinetic energy.

Energy cannot be created and destroyed, but it can be converted from one form to another. It can tend to spread or disperse until no part of the system has more than one part. Entropy is a measure of how much energy a particular system has dispersed. The entropy of the system increases on heat dispersal, as molecule tends to disperse. This is a measure of randomness.

The first law of thermodynamics states that “energy cannot be created or destroyed, but it can be transformed from one form to another form”. This law explains that organisms cannot produce energy; however, they constantly capture energy from their surrounding as open systems and covert this energy from one form to another form for biological work.

The second law of thermodynamics states that “no energy transfer is 100% efficient; some energy is dispersed as heat”. According to this law, entropy in the universe is continuously increasing. As the organisms are open systems, they maintain their ordered states over time with a constant energy input from their surroundings.