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as the temperature of a solid increases, what else increases?
velocity of the particles
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when are melting point and freezing point the same?
at the same pressure
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melting point
particles slip out of their organized pattern and the solid becomes a liquid
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freezing point
particles of the liquid move so slowly that they move back into an organized pattern
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vapor
particles move so fast that the liquid becomes vapor
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equilibrium
- that 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 the liquid
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saturated
when the liquid is in equilibrium with the vapor above it
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the high the temperature, the higher the _____ gases exert
pressure
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Le Chatelier's principle
- when a system in equilibrium is stressed, the system will react to relieve the stress
- change in temperature, pressure, and concentration
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vapor pressure
the pressure generated by a vapor that is in equilibrium with a liquid
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Low vp has what kind of intermolecular forces?
strong- hold particles tightly
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high vp has what kind of intermolecular forces
weak- hold particles weakly
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melting point (solid)
the temp at which the vp of the solid and the vp of the liquid are equal
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sublimation
- solids that vaporize quickly in air without going through the liquid phase
- dry ice, moth balls
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What happens when temperature rises in a lquid?
- vp and ke also increase
- molecules get pushed further apart
- bubbles of vapor form and the move to the liqid's surface
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normal bp
the vp in a system is equal to the standard atmospheric pressure- 101.3 kPa
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BP is a function of
- air pressure
- the lower the air pressure, the lower the bp
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what is the difference between boiling and evaporation?
- evaporation occurs at the surface
- boiling occurs throughout
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volatile
boils at low temp and evaporates quickly at room temperature
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non-volatile
boils at high temp and evaporates slowly at room temperature
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what kind of vp's do volatile liquids have?
high
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what kind of vp's do non-volatile liquids have?
low vp
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liquefaction
condensing substances that are normally gases at room temp to liquids- involves temp and pressure
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critical temp
- Tc
- temp above which no amount of pressure will result in the liquefaction of a gas
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critical pressure
- Pc
- the pressure that will cause a gas to liquefy at Tc
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Low Tc indicates
weak forces between molecules
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High Tc indicates
strong forces between between molecules
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phase diagram
shows the relationship between temperature, pressure, and physical state
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triple point
the temp and pressure at which all 3 phases are at equilibrium
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when energy is added to a solid, the temp of the solid increases until
Tm is reached
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the temperature of a melting solid doesn't change until
all of the solid is completely melted
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What does the energy added to a solid need to change?
the position of the particles- PE is increased
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enthalpy of fusion
the energy required to melt 1 gram of a substance at its Tm
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enthalpy of vaporization
the energy required to vaporize 1gram of a substance at its Tb
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melting and boiling points for molecules can be predicted with a knowledge of
the atomic and molecular structure
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melting and boiling points for molecules can be predicted with a knowledge of the atomic and molecular structures unless
- the molecules contain H that is covalently bonded to a highly electronegative atom
- highly polar molecule
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hydrogen bonding forms?
extremely strong dipole
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what does H bond with to form these dipoles?
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when is water most dense?
3.98 deg C
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what breaks H bonds?
melting
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in ice, one molecule of water is bonded to ____ other water molecules
5
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the clusers of hydrogen bonds in ice creat what?
- crystalline structure
- many open spaces
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surface tension is due to
the unbalanced forces on the surface particles of a liquid
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what kind of surface tension does water have?
high
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what kind of surface tension does mercury have?
low
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