Textbook Topic 9- Gas law Flashcards
Gas pressure is caused by… although the force is small…..
the force exerted by the gas molecules colliding with the surfaces of objects. Although the force of each collision is very small a large SA experience lots of collision in a short time causing high air pressure
Atmospheric pressure is caused by
the weight of the column of air molecules in the atmosphere above an objet
Pressure can be increased by (Not temp or volume) (2)
increasing force or decreasing the area
In terms of weather, low-pressure systems occur when (2)
the earths atmospheric pressure is lower than the surrounding environment
moist air rises and condenses producing clouds
as you go up the troposphere (3)
air density, air pressure and temp decrease
hydrostatic pressure
pressure by a fluid due to gravity
Ideal gas
a hypothetical construct that real gases approximate under certain conditions
effects of temp on the volume of a given amount of a confined gas at constant pressure
the volume increases as the temp increases and decrease as the temp decreases
This relationship between temperature and pressure is observed for any sample of gas confined to a constant volume
not go up and down
Temperature and pressure are linearly related and proportional is temp is in Kelvin
Boyle’s Law
The volume of a given amount of gas held at constant temp is inversely porprotional to the pressure under which it is measured
If volume increase by a certain factor, the pressure will_____ assuming ____ and _____ do not change
decrease by the same factor
moles and temp
Tell me how breathing works with the lungs and shit
Breathing occurs because the expanding and contracting of your lungs causes air pressure difference causing air to be drawn into and forced out
Avogadros law
For a confined gas the volume and number of moles are proportional if the pressure and temp remain the same
ideal gas law (3)
combining all the laws with p,v,,n,t
Pv=nRT
describes gas under ideal conditions
ideal conditions of gas us holds true to real life when conditions are:
gas is under low pressure and high temp
combined gas law when moles are the same
P1V1/T1=P2V2/T2
Combined gas law when moles are different
P1V1/n1T1=P2V2/n2T2
If the number of moles of an ideal gas are kept constant under two different sets of conditions, a useful
mathematical relationship called the combined gas law. In the combined gas law, both sets of conditions are equal to the product of….
moles(R)
nR
general units for combined gas law
atm, K, L
standard temperature and pressure
1 mole of an ideal gas have v=22.4L
p=1atm
T=273.15K
Difference between density and ideal gas law
Density is an characteristic determined by its identity
ideal gas law relates these properties in identical fashion regardless of the chemical identity of the gas
density formula
d= (molar mass)(p)/(RT)
Daltons’s Law of partial pressures+ equation
The total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of the component gases
Ptotal= Pa+Pb+Pc….
Each individual gas in a mixture exerts
the same pressure that it would exist if it were present alone in the container
the coefficient infront of the chemical equation signifies
the moles which is also equal to the volume
Kinetic molecular theory which one describes amonton law?
If the temperature is increased, the average speed and kinetic energy of the gas molecules increase. If the volume is held constant, the increased speed of the gas molecules results in more frequent and more forceful collisions with the walls of the container, therefore increasing the pressure
Kinetic molecular theory which one describes Charles law?
If the temperature of a gas is increased, a constant pressure may be maintained only if the volume occupied by the gas increases. This will result in greater average distances traveled by the molecules to reach the container walls, as well as increased wall surface area. These conditions will decrease the both the frequency of molecule-wall collisions and the number of collisions per unit area, the combined effects of which balance the effect of increased collision forces due to the greater kinetic energy at the higher temperature.
Kinetic molecular theory which one describes Boyles law?
If the gas volume volume of a given amount of gas at a given temperature is decreased (that is, if the gas is compressed), the molecules will be exposed to a decreased container wall area. Collisions with
the container wall will therefore occur more frequently and the pressure exerted by the gas will increase
The average speed of a gas depend
its molar mass—the lighter the mass, the faster the average speed.
speed of particles in a gas sample
not mass related one
individual molecules have varying speed but the molecular speed distribution (after an hour the curve is still the same) and average speed is constant (after 1 hour average speed is still the same).
Maxwell-Boltzmann
depicts the relative numbers of molecules in a bulk sample of gas that possesses a given speed
if temp of a gas increases,……+effect of the Maxwell-Boltzmann graph
its KE value also increase, more molecules have higher speeds and fewer molecules have lower speeds, and the distribution shifts toward higher speeds overall, that is, to the right.
Gases composed of lighter molecules have more…..+speed distribution (2)
high-speed particles
with a speed distribution that peaks at relatively higher speeds
Gases consisting of heavier molecules have more….+speed distribution (2)
more low-speed particles
a speed distribution that peaks at relatively lower speeds.
compressibility factor (Z)+ how do you know ideal gas law not accurate (2)
molar volume of gas at same temp+pressure/molar volume of ideal gas at same temp+pressure
any deviation from 1 is an indication of non-ideal behavior
when does ideal gas law fail
at relatively high pressures
how do real gas behaviour fail at Boyle’s law?
Boyles law states that as pressure increase, volume decrease.
gas forces in-between will decrease volume like suppose to but also decrease pressure which should have increased even more since u have this extra volume decrease
However, when the gases are crowded tgt with high pressure and low volume, they start sticking to eachother this decreases the pressure (if the volume is constant) or decreasing the volume (at constant pressure) (Figure 9.36). This change is more pronounced at low temperatures because the molecules have lower KE relative to the attractive forces, and so they are less effective in overcoming these attractions after colliding with one another.
