component: A distinct chemicalspecies in a mixture. If there are noreactions taking place, the number ofcomponents is the number of separatechemical species. A mixture ofwater and ethanol, for instance, hastwo components (but is a singlephase). A mixture of ice and waterhas two phases but one component(H2O). If an equilibrium reaction occurs,the number of components istaken to be the number of chemicalspecies minus the number of reactions.Thus, inH2 + I2→2HIthere are two components.