MECH 237 Chapter 3: Properties of Pure Substances

• School: CSU
• Department: Mechanical Engineering
• Course: MECH 237
• Professor: Daniel B.Olsen

Document Summary

Pure substance: a substance that has a fixed chemical composition throughout, Can be made of multiple chemical elements but is homogeneous. (ex: water, nitrogen, helium, carbon dioxide). A mixture of two or more phases of a pure substance is still a pure substance as long as the chemical composition of all phases is the same. There are three principle phases: solid, liquid and gas, a substance may have several phases within a principle phase, each differing in molecular structure: example: carbon, can exist as graphite or diamond in the solid phase. Phase: identified as having a distinct molecular arrangement that is homogenous throughout and separated from the others by easily identified boundary surfaces. Intermolecular bonds are strongest in solids and weakest in gases. Solids are packed tightly together whereas gases are spread out. Solids: arranged in a three-dimensional pattern (lattice) that is repeated throughout.