Skip to ContentGo to accessibility page
OpenStax Logo
Chemistry: Atoms First

Introduction

Chemistry: Atoms FirstIntroduction
Figure 17.1 An agama lizard basks in the sun. As its body warms, the chemical reactions of its metabolism speed up.

Chapter Outline

Introduction

The lizard in the photograph is not simply enjoying the sunshine or working on its tan. The heat from the sun’s rays is critical to the lizard’s survival. A warm lizard can move faster than a cold one because the chemical reactions that allow its muscles to move occur more rapidly at higher temperatures. In the absence of warmth, the lizard is an easy meal for predators.

We have now developed a relatively complete picture of chemical and physical processes, encompassing the contributions of energy (enthalpy changes) and entropy (order and disorder). Each ultimately contributes to the determination of reaction spontaneity – that is, whether or not a process will take place spontaneously. We have also looked at the important concept of zero free energy change, where a system comes to equilibrium. What we have not yet examined is whether a process reaches equilibrium quickly or slowly.

Consider, for example, the advertising slogan “Diamonds are forever.” Are they? A look at the table of enthalpy and entropy values tells us the thermodynamically stable form of carbon is actually graphite, not diamond. Further, a calculation shows us that the conversion of diamond into graphite is indeed a spontaneous process – the G value is negative. So why do we not see diamond spontaneously forming graphite? The answer is found in the topic of this chapter, chemical kinetics, which involves the rate at which reactions take place. It turns out that while the conversion of diamond into graphite is a spontaneous process, it occurs so slowly that we do not observe the conversion taking place on any time scale we know.

The study of chemical kinetics concerns the second and third questions—that is, the rate at which a reaction yields products and the molecular-scale means by which a reaction occurs. In this chapter, we will examine the factors that influence the rates of chemical reactions, the mechanisms by which reactions proceed, and the quantitative techniques used to determine and describe the rate at which reactions occur.

PreviousNext
Order a print copy
Citation/Attribution
Reuse and redistribution of this content in digital or print format:
  • This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's prior written permission.
  • This book uses the Creative Commons Attribution License, which means that you can reuse and modify the material only for noncommercial purposes, must attribute OpenStax, and must distribute any derivative works under the same license.
  • Any commercial printing of this textbook, including using a local or custom printer, must be approved by OpenStax, and proper citation provided.
  • OpenStax-copyrighted images, activities, assessments, and similar components of this book are subject to the same licensing – CC-BY-NC-SA. They can be used for noncommercial purposes with attribution. Commercial use requires permission.
  • Permission requests: Anyone who intends to incorporate this content (including text, images, and other components) into large language models, use it in AI offerings, use it commercially (including in print), and/or has questions about another use case is welcome to complete our reuse request form.
Attribution information
  • If you are redistributing all or part of this book in a noncommercial print format, then you must include on every physical page the following attribution:

    Access for free at https://openstax.org/books/chemistry-atoms-first/pages/1-introduction

  • If you are redistributing all or part of this book in a noncommercial digital format, then for every page that includes OpenStax content, you must license the derivative work under the same CC-BY-NC-SA license as the original, and include on every digital page view the following attribution:

    Access for free at https://openstax.org/books/chemistry-atoms-first/pages/1-introduction

Citation information

The information below includes the information needed to generate citations in most major styles (APA, MLA, etc.); you must reformat and organize the information as needed to fit the requirements of the style. Use the information below to generate a citation. We recommend using a citation tool such as this one.

© Feb 15, 2022 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License. The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo, and Rice University name, and Rice University logo trademarks, or wordmarks are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.