physical chemistry

pressure equals force divided by the area p=F/A
in science it is always measured in Kelvin (Celsius + 273.15 = Kelvin)
Equation of state for perfect gases
pV=nRT, at constant temperature boyles law p=1/V
Thermal equilibrium
When two bodies in contact have the same temperature and there is no net flow of energery between them
Each constant temperature curve on a graph of pressure versus inverse of volume (p = 1/V)
represent change in atmospheric pressure on a weather map, in increments of 4 mbar or 400pa
Compression factor
Z=Vm/Vm(perfect) // Vm = V/n = RT/p (this is molar volume equation volume divided by number of moles in that volume or R x temp divided by pressure) Z=pVm/RT
Van der Waals equation of state
p=(nRT/(V-nb))-a(n/V)^2 p=(RT/Vm-b)-a/Vm^2
potential energy vs particle separation
potential energy = mass x gravity x height gravity=9.81 m s^-2 Coulomb potential energy = Q1Q2/4 x pi x r
attractive and repulsive forces
critical temperature Tc
The temperature at which a gaseous state transforms continuously into the condensed state and at no stage is there a visible surface between the two states of matter (a gas cannont be condensed to a liquid by the application of pressure unless the temperature is below the critical temperature) vapour is the gaseous phase of a substance below its critical temperature
critical constants Tc,pc,Vc
All three of these temperature pressure and volume make up the critical constants
closed systems
can exchange energy but not matter with its surroundings
work w
a system does work when it causes motion against an opposing force w=mgh (mass x gravity x height) expansion work = p(external) x hA = p(external) x dV Work=-nRTln(Vfinal/Vinitial) Work=pdV (pressure x delta volume)
heat q
the process of transferring energy as a result of a temperature difference between the system and its surrounding q heat capacity c=q/dT or q=c x dT
internal energy U=q+w
internal energy (U) = heat + work heat (q)=
diathermic boundaries
Walls/boundaries that permit heating as a mode of transfer of energy
exothermic processes
a process in a system that releases energy as heat
first law of thermodynamics
The internal energy of an isolated system is constant
expansion work against constant pressure
expansion work for isothermal reversible process
Hydrostatic pressure
hydrostatic pressure = denstiy x height x gravity density = mass/volume
Equation of state for real gases
good to know
1 J = 1 Pa m^3
adiabatic boundaries
Walls/boundaries that do not permit heating even though there is a difference in temperature on both sides
endothermic process
a process in a system that absorbs energy as heat
open system
can exchange both energy and matter with its surroundings
isolated system
can exchange neither matter nor energy with its surroundings
pressure x area
partial pressure
xj = nj/n partial pressure = amount of j molecules in the mixture divided by the total amount
Maxwell distribution
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