Chapter 11: Liquids and Solids Flashcards
liquids and solids are …, in which matter occupies a large fraction of the …, causing the characteristic high … and low …
condensed states; sample volume; densities; compressibilities
solids and liquids are held together by
intermolecular forces
intramolecular forces are chemical bonds that hold
atoms and ions together in compounds
intermolecular forces affect the behavior of substances only when the molecules are
quite close together
the physical state of any sample of matter depends on the …. and the average … of the molecules
strengths of the intermolecular attractions; kinetic energy
the strengths of intermolecular attractions do not change much with
temperature
at any instant, some molecules have kinetic energies greater than the … and others have kinetic energies ..
average; less than the average
for gases energy of attraction is … kinetic energy of molecules
for liquids, energy of attraction is …. kinetic energy of molecules
=
for solids, energy of attraction is …. kinetic energy of molecules
> >
at a given temp, a solid has … intermolecular attractions than a liquid, whereas a liquid has … intermoleular attractions than a gas
stronger; stronger
the concept of distribution of energies also applies to molecules in the liquid state and is an important factor in evaporation, the conversion of molecules from the
liquid to the gas phase
to escape from a liquid, a molecule must have a kinetic energy that is sufficient to …
overcome the forces of attraction from the other molecules
for any temperature at which the liquid state is stable, only a small fraction of the moleules possess enough energy to evaporate, or vaporize– that is, have enough energy to
escape from the surface of the liquid
rate of evaporation depends on the
temperature of the liquid
the greater the temp, the greater the fraction of molecules that have …, and the faster the …
enough en ergy to evaorate; evaporation
condensation: conversion of a
gas to a liquid
the greater the number of gaseous molecules, the greater the rate of
condensation
when the rate of condensation equals the rate of evaporation, the pressure in the vessel …, the constant pressure that is achieved is called the … of the liquid
no longer changes; vapor pressure
a state of dynamic equilibrium is one in which two opposing changes occur
at equal rates (no net change is apparent)
at equilibrium, both … continue to occur
opposing processes
vapor pressure changes as the … changes
temperature
rate of evaporation and the equilibrium vapor presure … with increasing temperature
increase
boiling point of a liquid is the temperature at which the vapor pressure is
equal to the surrounding pressure
vapor pressure is the pressure at which the rate of
evaporation equals the rate of condensation
the boiling point is a function of the surrounding pressure– at lower surrounding pressures, a lower temperature is needed for the vapor pressure to
equal that pressure
the normal boiling point of a liquid is the temperature at which its equilibrium vapor pressure
equals one atmosphere
the stronger the intermolecular forces of attraction, the … the boiling point
greater
vaporization is an … process
endothermic
enthalpy of vaporization is the enthalpy change that accompanies the conversion of one mole of a substance from the
liquid state to the gaseous state at constant temp.
the higher the vapor pressure at a given temperature, the … the intermolecular forces
weaker
enthalpy of vaporization is
endothermic
the larger the enthalpy of vaporization, the … the intermolecular forces
greater
the enthalpy of vaporization of a liquid is the energy needed to separate the molecules by
overcoming the intermolecular attractions
the vapor pressure and rate of evaporation are low and the boiling point is high for a liquid with … intermolecular forces
strong
critical temperature is the maximum temperature at which a substance can
exist in the liquid state
above its critical temp., no matter how high the applied pressure, a substance has only
one phase that completely occupies the volume of the vessel.
critical pressure is the minimum pressure needed to … at the critical temperature
liquefy the substance
the single phase that exists above the critical temp and pressure is sometimes called a
supercritical fluid
the melting point of a substance is the temperature at which the
solid and liquid phases are in equilibrium
normal melting point is the temperature at which the solid and liquid phases are in equilibrium when the pressure is
1 atm
enhalpy of fusion is the enthalpy change that occurs when one mole of solid is converted to
liquid at a constant temperature
fusion is
endothermic
for any substance, the enthalpy of fusion is considerably … than the enthalpy of vaporization
smaller
the energy required for melting overcomes some of the intermolecular attractions, giving the molecules greater freedom of motion but much less freedom than they
would have in the vapor phase