Change in States of Matter &Energy Flashcards
Phase
part of a system that has uniform composition and properties (solid, liquid, gas)
Condensation
gas changes to a liquid
Vapor
a gas in contact with its liquid or solid phase
Equilibrium
a condition by which two opposing charges occur at equal rates in a closed system
(in a closed system) Equilibrium occurs when..
the rate of condensation is the same as the rate of evaporation
Equilibrium of Vapor Pressure is affected by:
- Concentration
- Temperature
- Pressure
Equilibrium Vapor Pressure of a Liquid:
the pressure exerted by a vapor in equilibrium with its liquid at a given temp
Vapor Pressure is measured using…
a mercury manometer
Because the forces of attraction are diff for diff liquids:
the quilibrium vapor pressure is specific for each liquid at a given temp
Volatile Liquids:
liquids that evaporate easily due to very weak forces of attraction
Nonvolatile Liquids:
liquids that do not evaporate easily - strong forces of attraction
Energy is always involved when:
physical or chemical change occurs
Energy can be in forms of:
heat and ligt
Law of Conservation of Energy:
energy can be absorbed or released in a change, but never destroyed or created
Vaporization:
the process by which a liquid changes to a gas
Two Types of Vaporization:
Evaporation and Boiling
Evaporation:
at the liquids surface
Boiling:
the change of a liquid to a gas within the liquid and at its surface
Boiling Point:
the temp at which the equilibrium vapor pressure of the liquid = the atmospheric pressure (surroundings)
Lower atmospheric pressure =
lower boiling point
Normal Boiling Point (n.b.p):
the boiling point of a liquid at standard atmospheric pressure (1atm, 760torr, or 101.3 kPa)
n.b.p of water:
100 C
n.b.p. for ethyl alcohol
100 C
Boiling & Evaporation are _________- physical change processes
endothermic
Endothermic:
energy must be added in order for the change to take place
Liquid + energy ->
gas
Condensation Is a _______ physical change process
exothermic
Exothermic:
energy must be removed in order for the change to take place
gas -> liquid + ______
energy
Heat of Vaporization:
the amnt of heat energy needed to boil 1 gram of liquid at the substance’s boiling point
Heat of Vaporization for Water:
2260 J/g
Heat of vaporization formula:
q = mHvap
q= energy (J)
m= mass
Hvap= heat of vaporization 8
Freezing:
physical change from a liquid to a solid
Energy:
Freezing involves loss of energy
The normal freezing point (n.f.p):
the temp at which the solid and liquid are in equilibrium at standard atmospheric pressure
At equilibrium, melting and freezing occur…
at equal rates
Melting is an ________ physical change process
endothermic
Freezing is an _______ physical change
Exothermic
solid + ____ -> liquid
energy
Heat of fusion:
the amnt of heat energy required to melt 1 gram of solid at the substance’s melting point
Heat of Fusion for water:
334 J/g
Heat of Fusion formula :
q = mHfus
In low temp and low pressure conditions a liquid…
cannot exist
In low temp and low pressure conditions a solid….
exists at equilibrium with it vapor —instead of its liquid
SUblimation:
the change of state from a solid directly to a gas
Deposition:
(the reverse process) the change of state from a gas directly to a solid
Triple Point:
point at which all three states of matter are in equilibrium - exist at same time
Critical point:
the critical pressure & temp of a substance
Critical Temp:
The temp above which the substance cannot exist as a liquid
Critical pressure:
the lowest pressure at which the substance, at critical temp, can exist as a liquid
