ABSTRACT
Properties of mixtures and changes in thermodynamically quantities when mixtures are formed are, however, of general importance. The enthalpy of a substance is thereby equal to the enthalpy difference between the substance and the elements it consists of. This chapter explains about entropy, enthalpy, and Gibbs energy in a particularly important application, namely, chemical reactions. The conversion between the cis and trans forms is achieved by rotation around the double bond. Of the two isomers, cis-butene has the highest energy for spatial reasons; the two methyl groups are quite bulky and repel each other as they sit on the same side of the molecule. The essential matter for the equilibrium properties is, however, mainly the difference in energy between the two minimum points.
