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as the temp of a solid increases, so does the
velocity of the particles
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melting point
the point at which particles slip out of their organized pattern and the solid becomes a liquid
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freezing point
the point at which the particles of the liquid move so slowly that they move back into an organized pattern
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When does MP = FP?
at the same pressure
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at some temperature, liquid particles move so fast that they escape the surface to form
vapor
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equilibrium
- the state in which 2 opposing processes occur at an equal rate
- requires a closed system
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dynamic equilibrium
particles are constantly moving from or returning to liquid
-
saturated
when a liquid is in equilibrium qith the vapor above it
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the higher the temperature, the higher the
pressure
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Le Chatelier's Principle
- when a system in equilibrium os subjected to a change (stress), the system will react to relieve the stress
- change in temperature
- pressure
- concentration
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vapor pressure
the pressure generated by a vapor that is in equilibrium with a liquid
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substances with low vapor pressures have what kind of intermolecular forces?
strong- hold particles tightly
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substances with high vapor pressures have what kind of intermolecular forces?
weak- hold particles weakly
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melting point of gas
the temp at which the vp of the solid and the vp of the liquid are equal
-
sublimation
- solids that vaporize quickly in air without going through the liquid phase
- dry ice, moth balls
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when heated, vp and ke
increase
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what happens when the vp and ke of a liquid increase?
the molecules get pushed further apart, bubbles of vapor form and move to the surface
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Normal BP
when the vp in a system is equal to the standard atmospheric pressure (101.3 kPa)
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difference between evaporation and boiling
evaporation is at the surface, boiling is throughout
-
volatile
- liquid boils at low temp and evaporates quickly at room temp
- ethyl alcohol
- ether
-
non-volatile
- boil at high temp and evaporate slowly
- molasses
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what kind of vp's do volatile liquids have?
high vp
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liquefaction
condensing substances that are normally gases at room temp to liquids- involves temp and pressure
-
critical temperature
- Tc
- temp above which no amount of pressure will result in the liquification of a gas
-
critical pressure
- Pc
- the pressure that will cause a gas to liquefy at Tc
-
Low Tc indicates
weak forces between molecules
-
high Tc indicates
strong forces between molecules
-
phase diagram
shows the relationship between pressure, temp, and physical state
-
triple point
the temp and pressure at which all 3 phases are at equilibrium
-
when energy is added to a solid, the temp increases until
Tm is reached
-
the temp of a melting solid doesn't change until
all of the solid is completely melted
-
the energy added to melt it is needed to change
- the positions of the particles
- PE increases
-
Enthalpy of fusion
energy required to melt 1 gram of a specific substance at its Tm
-
-
Enthalpy of vaporization
energy required to vaporize 1 gram at its Tb
-
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melting and boiling points for molecules can predicted with a knowledge of
the atomic and molecular structure
-
when the molecules contain H and it's covalently bonded to a highly electronegative atoms, it forms
a highly polar molecule
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Hydrogen bonding forms an
extremely strong type of dipole
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Hydrogen strongly bonds with... and forms
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water has what kind of density
most- 3.98 deg C
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what breaks the hydrogen bonds?
melting
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what do the clusters of hydrogen bonds make?
crystalline structure with many open spaces
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what is surface tension caused by?
unbalanced forces on the surface particles of a liquid
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is surface tension high or low for water?
very high
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is surface tension high or low for mecury?
very low
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