| A | B |
|---|
| Pure substance | a substance that has a fixed chemical composition throughout |
| pure | a mixture of various chemical elements or compounds that is homogenous qualifies as a ____ substance |
| chemical composition | 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 |
| principal phase | even though there are three _____, solid, liquid, and gas, a s ubsance may have several phases within a ____, each with a different molecular structure |
| phase | a ____ is identified as having a distinct molecular arrangement that is hmogenousthroughout and separated from the others by easily identifiable boundary surfaces |
| solids, gases | intermolecular bonds are strongest in ___ and weakest in ____ |
| solid | the molecules in a ___ are arranged in a three-dimensional pattern that is repeated throughout. Because of the small distances between molecules in a ___, the attractive forces of molecules on each other are large and keep the molecules at fixed positions. |
| oscillate, temperature | even though the molecules in a solid cannot move relative to each other, they continually ____ about their equilibrium positions. The velocity of the molecules during these oscillations depends on the ____ |
| liquid | the molecular spacing in the ___ phase is not much dfferent fom that of the solid phase, except the molecules are no longer at fixed positions relative to each other, and they can rotate and translate freely |
| gas | in the ___ phase, the molecules are far apart from each other, and a molecular order is nonexistent. |
| intermolecular forces | particularly at low densities, the ____ of a gas are small, and collisions are the only mode of interaction between molecles |
| gas molecules | _____ are at a considerably higher energy level than they are in the two other phases. |
| compressed/subcooled liquid | liquid that is not about to vaporize |
| saturated liquid | a liquid that is about to vaporize |
| boiling, pressure | once ____ starts, the temperature of the liquid/container stops rising until the liquid is completely vaporized (ie: the temperature will remain constant during the entire phase-change process if the ____ is held constant |
| saturated vapor | a vapor that is about to condense |
| saturated liquid-vapor mixture | a substance in both liquid and vapor phases coexisting at equilibrium |
| superheated vapor | a vaport that is not about to condense |
| pressure | the temperature at which water starts boiling depends on the ___. Therefore, if the ___ is fixed, so is the boiling temperature |
| saturation temperature | at a given pressure, the temperature at whihc a pure substance changes phase is called the ________ |
| saturation pressure | at a given temperature, the pressure at which a pure substance changes phase is called the ______ |
| saturation tables | _____ are tables that list the satureatioon pressure against the temperature |
| latent heat | the amount of energy absorbed or released during a phase-change process |
| latent heat of fusion | the amount of energy absorbed during melting; it is equivalent to the amount of energy released during freezing |
| latent heat of vaporization | the amount of energy absorbed during vaporization; equivalent to the amount of energy released during condensation |
| liquid-vapor saturation curve | a plot of Tsat versus Psat |
| higher pressures, higher temperatures | a substance at ______ boils at _______ |
| elevation | the atmospheric pressure and thus the boiling temperature fo water decreases with _____ |
| saturation pressure, pressures, lower temperatures | in vaccum cooloing, the temperature in the chamber remains constant until _____ is reached. Afterward, saturation conditions are maintained inside at progressively lower _____ and corresponding _____ until the desired temperature is reached |
| vacuum cooling becomes _____ if the pressure in the vaccum chamber is dropped below the saturation pressure of water | vacuum freezing |
