Unit 2: Gases, Liquids, and Solids Flashcards
pressure
the force exerted by a gas on a container
what are the four units of pressure? Which two are honors level?
- mmHg
- torr
- atm
- kPa
Name the three characteristics of a gas
- uniformly fills any container
- mixes completely with any other gas
- exerts pressure on it’s surroundings
the amount of pressure exerted is dependent on the…
kinetic energy of the particles
Name the four parts of the Kinetic Molecular Theory
- All gases move in random, straight-line motion separated by empty space
- Collisions between gas particles will result in a transfer of energy, but the overall energy remains constant. Collisions of particles with container walls cause the pressure exerted by gas.
- Volume of an individual particle is approx. 0
- Particles exert no forces on each other
real gases have…
volume, mass, and have an attraction for other particles.
under what conditions of pressure and temperature do you have to correct for ideal gas behavior?
low temperature and high pressure
what is vanderwaal’s equation
corrected pressure x corrected volume = nRT
what is the purpose of vanderwaal’s equation?
to correct real gases to give the exact pressure and volume of an ideal gas.
what is the universal or ideal gas law?
PV = nRT
what is the expression for corrected pressure?
observed pressure minus ‘a’ times (‘n’ divided by volume)^2
what is the expression for corrected volume?
the observed volume minus ‘n’ times ‘b’
what is the constant ‘a’ from vanderwaal’s equation related to?
related to pressure, specific to that gas
what is the constant b related to?
related to the attraction between molecules, also specific to the gas.
what does ‘n’ stand for?
the number of moles
what does ‘M’ stand for?
GFM, i.e. gram formula mass, molar mass… etc.
what is the “formula” for pressure?
force/area
when temperature increases, KE increases, and pressure…
increases
effective collision
a collision that creates a new product (some collisions are not strong/direct enough to break bonds and change the structure of the particles)
What does GFM stand for? What are some other names for it?
gram formula mass
- molecular mass
- formula weight
- molar mass
what are the units for GFM?
grams per mole (g/mol)
what is the ‘state’ of a gas?
the condition of the gas at a given time
what is the universal/ideal gas law and what is it used for?
PV = nRT, an equation of state for a gas
are moles applicable to sig figs??
NOO
formula for moles?
grams of substance / GFM of substance
what is a hydrate?
a substance where water is part of the equation, connected with a not-multiplication sign.
anhydrate?
version of a hydrate with the water removed.
what unit of pressure MUST be used with the ideal gas law?
atm. If it is kPa, CONVERT IT
what is the constant R?
0.0821
what unit of temperature must be used for PV = nRT and V/T?
Kelvin, convert if Celsius
ideal gases/ideal gas model
where the volume of the gas particles are negligible and there are no attractive forces between ideal gas particles because of the amount of space between them.
under what conditions of temp and pressure would a real gas behave like an idea one?
high temperature and low pressure
under what conditions will an ideal gas behave like a real one?
low temperature and high pressure.
what is the formula for density in terms of molar mass and the ideal gas law?
D = (MP/RT)
remember- PRESSURE MUST BE IN UNITS OF atm
- TEMP MUST BE KELVIN
law of partial pressures
in a sealed container with a mixture of different gases, each type of gas exerts it’s own pressure. The pressure exerted by each gas is called partial pressure.
how to find total pressure
add up all the partial pressures
the partial pressure of each gas in a mixture (when you have the total pressure) is dependent on the…
number of moles
how to find the partial pressure
- multiply the total pressure by the number of moles of the gas you want the pressure of divided by the total number of moles
- OR plug into original equation and subtract their totals to find it
how many torr and mmHg are in 1 atm?
760
Avogadro’s Hypothesis
Equal volume of different gases at the same temperature and pressure have an equal # of molecules
how many particles are in one mole of gas?
6.02 x 10^23
how many Liters are in one mole of gas at STP?
22.4 L
STP
Standard temperature and pressure (273 K and 1 atm/ 101.3 kPa
how would you find the GFM of one element
it is just the number of atoms present x the atomic mass. BE CAREFUL - TAKE NOTE OF THE DIATOMIC ELEMENTS
EQUAL VOLUME =
EQUAL PRESSURE
What is the combined gas law formula?
P1V1/T1 = P2V2/T2
what temperature unit must you use with the combined gas law?
kelvin
do units for pressure and volume matter when using the combined gas law?
NOPE
what is boyle’s law?
P1V1 = P2V2, where T is constant
why does boyle’s law hold precisely only at very low pressures?
because the gas would behave more ideal
what equipment did they use to find Boyle’s law?
a J-tube
charles’s law
the volume of a gas is directly proportional to temperature and extrapolates to 0 at 0 kelvin
what is formula for charles’s law?
V1/T1 = V2/T2
what is Avogadro’s law?
for a gas at constant temperature and pressure, the volume is directly proportional to the number of moles of gas.
what is the formula for Avogadro’s law, derived from PV = nRT
V = an
diffusion
describes the mixing of gases. the rate of diffusion is the rate of gas mixing.
effusion
the passage of gas into an evacuated chamber.
what factors effect diffusion and effusion rates?
particle size and density.
what is Graham’s Law of Diffusion/Effusion
sqrt(M2)/sqrt(M1) (for the THEORETICAL) rate
properties of liquids
- stronger intermolecular forces of attraction that gases
- indefinite shape
- definite volume
- all liquids EVAPORATE at their surface
- if T increases there is a KE increase and evaporation increases
boiling point
when the atmospheric pressure is equal to the vapor pressure (Table H)
normal boiling point
the boiling point of a liquid at STP
surface tension
the resistance of a liquid to increase in its surface area
why does surface tension exist/why don’t the molecules of the liquid spread out?
because the intermolecular forces of attraction between the molecules are stronger than the object that it is attached to.
what is the strongest kind of intermolecular bond?
hydrogen bond
capillary action
the spontaneous rising of a liquid in a narrow tube
viscosity
the resistance of a liquid to flow
what causes viscosity?
intermolecular forces of attraction (the stronger the attraction, the more viscous the liquid
properties of solids
- definite shape and volume
- strongest intermolecular forces of attraction
- particle is located in a fixed position, vibrating
- have a crystalline structure with geometric patterns when viewed with a microscope
what are two kinds of odd solids?
amorphous and super cooled Liquids
amorphous
solids that lack ordered structure, like rubber and plastics
super cooled liquids
cooled to a rigid state without crystallizing