Gases and Thermo Flashcards
gases
a collection of particles moving at random through a primarily empty space
gas pressure
force exerted by the collisions of randomly moving particles with the walls of a container
1 atm = ___ mmHg = _____torr
760
avagadros law
volume of a gas at constant T and P is proportional to the number of moles of gas
boyles law
volume of a fixed amount of gas at a constant temp is inversely proportional to pressure
charles law
volume of a fixed amount of gas at a constant pressure is proportional to the absolute temp
standard temp and pressure
0C and 1 atm
partial pressure
the pressure a gas would have if it was the only gas in the container
daltons law of partial pressures
total pressure is equal to the sum of the partial pressures
the fraction of the total pressure contributed by each gas is equal to its
mole fraction
5 rules of kinetic molecular theory of gases
- a gas consists of tiny particles moving at random
- the volume of these particles themselves is negligible compared to the total volume
- gas particles act independently of eachother
- collisions of gas particles are elastic
- average kinetic energy of the particles is proportional to the Kelvin temp
elastic collisions
bounce off of other things at the same speed at which they hit
gas diffusion
the mixing of different molecules by random molecular motion with frequent collisions
gas effusion
gas molecules escape without collisions through a tiny hole into a vacuum
what two assumptions about gases are not valid at high temps
- that the volume of a pas particles is negligible
- that there are no attractive forces between particles
phase changes
change of state
fusion (solid-liquid)
ΔH +
ΔS +
freezing (liquid-solid)
ΔH -
ΔS -
vaporization (liquid-gas)
ΔH +
ΔS +
condensation (gas-liquid)
ΔH -
ΔS -
sublimation (solid-gas)
ΔH +
ΔS -
deposition (gas-solid)
ΔH -
ΔS -
if both ΔH and ΔS are +, reaction is favored at
high temp
if both ΔH and ΔS are -, reaction is favored at
low temp
thermochemistry
the absorption or release of heat that acompanies chemical reactions
energy
the capacity to do work
mechanical kinetic energy
moving mass
electrical kinetic energy
moving charge
sound kinetic energy
molecules moving uniformly
heat kinetic energy
molecules moving randomly
mechanical potential energy
mass in a place where a force can act
chemical potential energy
bonds
binding potential energy
binding energy
1st law of thermodynamics
energy cannot be created or destroyed (potential and kinetic energy are conserved)
the total energy of an isolated system is
constant
system
reactants and products
surrounding
everything other than the reactants and products
-ΔE
system lost energy to surroundings
+ΔE
system gained energy from surroundings
+q
gains heat
-q
loses heat
+w
work on system
-w
work done by system
work
the force that produces the movement of an object times the distance moved
pressure-volume work
expansion work, done as a result of a volume change is the system
calorimetry
measuring ΔH
heat capacity (c)
amount of heat required to raise an objects temp by 1K
expansion
w≤0
ΔE≤0
ΔV>0
compression
w>0
ΔE>0
ΔV<0
ΔH=q at
constant pressure
molar heat capacity
heat capacity of one mole of a substance
specific heat capacity
heat capacity of one gram of a substance
isothermal process
a change of a system in which the temp remains constant
adiabatic process
a system exchanges no heat with the suroundings
in an isothermal process ΔE =
0
in an adiabatic processs q=
0
