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
why does water form a droplet (surface tension)
a droplet has the smallest surface area for its volume, minimising the surface energy
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
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
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
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
