chapter 10, section 4 changes of state. phase any part of a system that has uniform composition...
TRANSCRIPT
Chapter 10, Section 4
Changes of State
Phase
Any part of a system that has uniform composition and properties.
Condensation
Process by which a gas changes to a liquid
Equilibrium
Dynamic condition Two opposing changes occur at equal rates in a closed system
Equilibrium Vapor Pressure
The pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temperature.
Volatile Liquids
Evaporate readilyWeak forces of attraction between their particles.
Example: ether
BOILING:
Vaporization (appearance of bubbles) throughout a liquid.
BOILING POINT
The temperature at which the vapor pressure of the liquid is just equal to the atmospheric pressure.
Molar Enthalpy of Vaporization
Amount of energy needed to vaporize one mole of liquid at the liquid’s boiling point at constant pressure
ΔHv
FREEZING: The physical change of a
liquid to a solid by removal of energy as heat.
As a liquid cools, the KE decreases & particles are pulled together in a more orderly arrangement – a solid.
FREEZING POINT
The temperature at which the solid & liquid are in equilibrium at 1 atm (atmosphere) of pressure.
MELTINGThe opposite of freezing
The physical change of a solid to a liquid by the addition of energy.
The melting and freezing points for a substance are at the same temperature.
H2OFreezes at 0oCMelts at 0oC
Molar Enthalpy of Fusion
The amount of energy required to melt one mole of solid at the solid’s melting point
ΔHf
Sublimation
The change of state from a solid directly to a gas
Example: dry ice (CO2)
Deposition
The change of state from a gas directly to a solid.
Example: frost
Phase Diagram
Figure 16; Page 347