137A- states of matter Flashcards
What are the assumptions of an ideal gas
no energy transfer when molecules bump into each other or wall/ no IMF between molecules/ small amount of mass and no volume/ constant random motion/ distanced between mol > size of mol
what are the units of PV=nRT
P= Nm-1 or Pa
V= m3
T= K
n= mol
R= JK-1mol-1
What are the units of R = 8.31
JK-1mol-1
what does JK-1 mean in qualitive terms
energy per unit temperature (how much energy something has per unit K)
What is the calculation to get R=8.31
Boltzmann constant x avagadros constant
define pressure
force per unit area
moles calculation triangle
PV=nRT is how an ideal gas behaves. A real gas will act more like an ideal gas the closer P is to….
0
what is the root mean path of a molecule
distance travelled before colliding with another molecule
units of rms equation
M= mNA=0.0202 kg mol-1
C (u) = ms-1
How much energy do molecules have at 0K
no energy
what is PV=nRT in graph form
Why do ideal and real systems deviate?
-assumed molecules have negligible volume.-true for low P and high T; at opposite the volume of gas decreases and therefore volume of molecules becomes more significant
-assumed IMF are negligible- Sometimes at low T and high P condensed phases form. Ideal laws deal with gases
triangle for molar volume, volume and moles
Define phase
a homogenous part of a system seperated by a boundary form other parts of the systems
What is the triple point
T and P where solid, liquid and gas phases are in equilibrium
What do the lines on a phase diagram graph show
where the phases are in equillibrium
What does the critical temp represent
gas+liquid become indistinguishable; solvates like a liquid but has the diffusivity of a gas
what is a normal boiling point
bp at 1atm
what is 1 bar in Pa
1x10^5
what is daltons law
total pressure exerted by a mixture of gases is the sum of the individual partial pressures
what are some properties influenced by IMF
melting point, bp, viscosity, surface tension, cohesion/adhesion
what are adhesive forces
attraction of molecules to surface
what are cohesive forces
attraction of molecules to each other
why does water form a droplet (surface tension)
a droplet has the smallest surface area for its volume, minimising the surface energy
why does water have an unusually high surface tension (surface tension depends on IMF)
hydrogen bonding between molecules
define the terms in Columbus law
F= force experienced by q due to presence of q2 (Jm-1)
q= charge 1 (C)
q2= charge 2 (C)
r= distance between atoms (m)
what does the subscript ‘r’ mean
force is dependant on r
what is ε0 in the equation
perceptivity of a vacuum; describes a system if two charges were separated by vacuum
how to work out the perceptivity of a material
ε = εr x ε0 where εr= dimensionless relative perceptivity
why does U∝ 1/r
the smaller the distance the larger the U
What are the units
U= Nm or J (energy of interaction)
q= C
r = m
why are ionic interactions the strongest
they act over the largest distance
describe this graph
-the more we pull the atoms apart the more they want to want to spring back together towards equilibrium
-the further apart=their potentials energies increase
-so we need to exert more more and E on them to pull them further
-equilibrium=0; lowest energy state of the system
what the units for the equation of dipole moment
μ= Cm
q= C
r= m
why does methane not have a dipole moment despite having polar bonds
no “positive” or “negative” end
what is this equation used for and units
the energy of interaction for 2 molecules with dipoles
U=Nm or J
μ= must convert from D to cm
Kb= Boltzmann constant
relationship between U and r
equations relating U and r for all of these interactions
define polorizability
degree to which an electron cloud is influenced by an incoming dipole or an electric field
what effects how easily an electron cloud can be polarised by another molecule
electron arrangement- if electrons are closely bound to nucleus they cannot move around as much as e- that are further away
what is the equation for P (induced dipole moment)
where ∝ is polorizability
draw a heating cooling curve
partial pressure equation
free energy of mixing
what does the activity co-efficient tell us
