SoMixtureideal gases far, single-component fluids have been analysed, i.e. fluids consisting of one chemical component. Part I of the book addressed ideal gases and incompressible liquids, which typically existed as single-component fluids. In Chap. 18 , fluids that undergo a phase change have been investigated, i.e. a fluid can occur in a solid, liquid and gaseous state—but its chemical composition remains constant even during a phase change.