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Chapter

Cover Making the Transition to University Chemistry

Thermochemistry  

This chapter focuses on thermochemistry. It starts with enthalpy change which is the heat added to a system at constant pressure. The reaction is considered endothermic if heat is taken, while it would be exothermic if heat is given out. As the chapter shows, a calorimeter can be used to measure enthalpy changes. According to Hess's law, the standard enthalpy change for a reaction is independent of the route taken from reactants to products. Atomization enthalpy, on the other hand, is the standard enthalpy change accompanying the formation of a gaseous atom from either a solid or a gas containing molecule. Finally, the chapter explains bond enthalpy, solution enthalpy, and hydration enthalpy as well.

Book

Cover Thermodynamics of Chemical Processes
Thermodynamics of Chemical Processes describes the basic principles which govern reactivity and phase equilibria in chemical systems and contains a number of worked examples and problems. The first chapter considers preamble energy in chemical systems. The second chapter covers enthalpy and thermochemistry. The next chapter is about entropy in chemistry. There follows a chapter on free energy and equilibrium. The last chapter is about phase changes and solutions.

Chapter

Cover Elements of Physical Chemistry

Chemical change  

This chapter explores thermochemistry, one of the principal applications of thermodynamics to chemistry. It begins by looking at how the strengths of bond are expressed in terms of the bond dissociation enthalpy and their mean values over a series of related compounds. The chapter then considers the standard enthalpy of combustion, which is the change in standard enthalpy per mole of combustible substance. Meanwhile, the reaction enthalpy is the change in enthalpy that accompanies a chemical reaction. The standard reaction enthalpy (the ‘standard enthalpy of reaction’) is the value of the reaction enthalpy when all the reactants and products are in their standard states. The chapter also discusses Hess's law, the standard enthalpy of formation, exothermic and endothermic compounds, and Kirchhoff's law.

Chapter

Cover Atkins’ Physical Chemistry

Thermochemistry  

This chapter assesses thermochemistry, which is the study of energy released or absorbed as heat during chemical reactions and how it depends upon the conditions. Thermochemistry is a branch of thermodynamics because a reaction vessel and its contents form a system, and chemical reactions result in the exchange of energy between the system and the surroundings. The chapter begins by looking at enthalpies of physical and chemical changes. It explains Hess's law, according to which the standard reaction enthalpy is the sum of the values for the individual reactions into which the overall reaction may be divided. The chapter then considers the standard enthalpy of formation, as well as the temperature dependence of reaction enthalpies. It also discusses differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC).