CH E243 Chapter 3: CHE243Ch3PropertiesofPureSubtances

• School: University of Alberta
• Department: Chemical Engineering
• Course: CH E243
• Professor: Glaucia Carvalho Do Prado

Document Summary

Pure substance: a substance that has a fixed chemical composition throughout e. g. water, nitrogen, helium, carbon dioxide. A pure substance does not have to be of a single chemical element/compound. A mixture of various chemical elements/compounds also qualifies as a pure substance as long as the mixture is homogeneous. A mixture of 2/more phases of a pure substance is still a pure substance as long as the chemical composition of all phases is the same. Phase: is identified as having a distinct molecular arrangement that is homogenous throughout and separated from the others by easily identifiable boundary surfaces. Intermolecular bonds are strongest in solids and weakest in gases molecules in solids are closely packed together, whereas in gases they are separated by relatively large distances. The molecules in a solid are arranged in a 3-d pattern (lattice) that is repeated throughout.