Collections:Texts:Chemistry:Chapter 15 - Thermodynamics: Atoms, Molecules, and Energy
From ChemEd Collaborative
THERMODYNAMICS: ATOMS, MOLECULES, AND ENERGY
15.5 Fossil Fuels and the Energy Crisis
In Chap. 3 we indicated that heat is a form of energy and showed how the quantity of heat energy absorbed or released by a chemical change could be related to the corresponding chemical equation. We also stated the law of conservation of energy, and arguments in subsequent chapters have often been based on the idea that energy can neither be created nor destroyed. The law of conservation of energy is the first of three important laws involving energy and matter, which were discovered over a century ago. These laws were originally based on the movement or transfer (dynamics) of heat (thermo),and the law of conservation of energy is therefore referred to as the first law of thermodynamics. In this chapter we will discuss many of the important applications of the first law to chemistry. Chapter 16 will define and apply the second and third laws.
In Chap. 3 we assigned the symbol ΔH and the name enthalpy change to the quantity of heat absorbed by a chemical or physical change under conditions of constant pressure. You may have wondered at that time just how heat energy could be absorbed or given off when atoms and molecules changed position and structure during a chemical reaction, but we had not yet developed theories of chemical bonding, molecular structure, intermolecular forces, and molecular motion to the point where a satisfactory explanation could be given. Now we are in a position to investigate what can happen to molecules when matter absorbs or releases heat. One result of this study will be a clearer understanding of enthalpy. At the same time we will begin to appreciate what molecular factors contribute to making a reaction exothermic or endothermic. This will give us a solid basis for discussing several aspects of what is probably the most important problem facing our technological society today―the energy crisis.
Go to previous | Go to start of chapter | Return to Table of Contents | Go to next
