Ch. 6- Gases, Liquids, Solids, and Intermolecular Forces Flashcards
melting point
the temperature at which a substance changes from the solid to the liquid state
boiling point
the temperature at which the pressure of the vapor escaping from a liquid equals the outside pressure
vaporization
the process by which a substance changes from the liquid to the gaseous state
condensation
the process by which a substance changes from the gaseous state to the liquid state
freezing
the reverse of melting; changing from the liquid to the solid state
sublimation
conversion of a solid directly to the gaseous state without going through the liquid state
deposition
the direct formation of a solid from a gas without passing through the liquid state; reverse of sublimation
dipole-dipole forces
the attractive forces that exist among polar covalent molecules
dispersion forces
the momentary, usually weak attractive forces between molecules resulting from electron motions that create short-lived dipoles
dispersion forces
the momentary, usually weak attractive forces between molecules resulting from electron motions that create short-lived dipoles
where can dispersion forces exist?
between ANY two particles that have electrons (whether they’re polar, nonpolar, or ionic)
hydrogen bond
a type of intermolecular force in which a hydrogen atom covalently bonded in one molecule is attracted to a nonmetal atom in a neighboring molecule; both the atom to which the hydrogen atom is bonded and the one to which it is attracted are small, highly electronegative atoms, usually N, O, or F
how do we know if dipole-dipole forces exist between molecules?
if the molecules are polar, and hydrogen bonding is not possible
how do we know if dispersion forces exist between molecules?
if the molecules are nonpolar, because nonpolar molecules can ONLY exhibit dispersion forces, and no other forces
how do we know if hydrogen bonding exists between molecules?
if the molecules are polar, and they consist of H covalently bonded to N, O, or F in one molecule, and N, O, or F in a polar bond in a neighboring molecule
how do intermolecular forces range in strength?
weakest–>strongest
dispersion forces, dipole-dipole forces, hydrogen bonding
kinetic-molecular theory
an explanation of the behavior of gases based on the motion and energy of particles; includes 5 basic concepts:
- particles of a gas (usually molecules, but atoms in the case of noble gases) are in rapid, constant motion and move in straight lines
- the particles of a gas are tiny compared with the distances between them
- because the particles of a gas are so far apart, there is very little interaction between them
- particles of a gas collide with one another & energy is conserved in these collisions (because energy lost by one particle is gained by the other)
- temperature is a measure of the average kinetic energy (energy of motion) of the gas particles
Boyle’s Law
states that for a given mass of gas at constant temperature, the volume varies inversely with the pressure; PV=k; first gas law created
William Thomson
Scots-Irish physicist who created an absolute temperature scale known as the Kelvin scale, which has -273.15°
Charles’s Law
states that for a given mass of gas at constant pressure, the volume varies directly with the absolute temperature; V/T=k
Gay-Lussac’s Law
states that the pressure of a fixed amount of gas at fixed volume is directly proportional to its temperature in kelvins; P/T=k
Avogadro’s Law
states that at a fixed temperature and pressure, the volume of a gas is directly proportional to the amount (# of moles) of gas; V/n=k
molar volume
the volume occupied by 1 mol of a substance (usually a gas) under specified conditions
standard temperature and pressure (STP)
conditions of 0°C and 1 atm pressure
at STP, how much can 1 mol of any gas occupy?
22.4L
combined gas law
the single relationship that incorporates the simple gas laws; PV=kT
ideal gas law
states that the volume of a gas is proportional to the amount of gas and its Kelvin temperature, and inversely proportional to its pressure; PV=nRT
what is “the gas constant”?
R = 0.0821 (L x atm)/(mol x K)
