20 Gases Flashcards
Boyle’s law
States that for a fixed mass of gas at constant temperature
pV = constant
Measurements plotted as a graph of pressure against 1 / volume gives a straight line through the origin
Charles’ law
For a fixed mass of an ideal gas at constant pressure, its volume is directly proportional to its absolute temperature
V / T = constant
Work done = p 🔺v
Isobaric change
Any change at constant pressure
Isothermical
Any change at constant temperature
Pressure law
For a fixed mass of ideal gas at constant volume, its pressure is directly proportional to its absolute temperature
P / T = constant
Brownian motion
The random and unpredictable motion of a particle such as smoke particle caused by molecules of the surrounding substance colliding at random with the particle. Its discovery provided evidence for the existence of atoms
Avogadro constant
The number of atoms in 12g of the carbon istope 12 carbon is defined as a mole. The value is 6.02 x10^23
Pressure
Pressure of gas is the force per unit area that the gas exerts normally
Molarity
number of moles of a certain quality of a substance
ideal gas equation
Pv=nRT
molar gas constant
8.31
plot a graph of pV against T
line with the gradient = nR
Boltzmann constant (k)
molar gas constant divded by the avogardo number
1.38*10-23
Root mean square speed
square root of the mean value of the square of the molecular speeds.
Crms = [ C1^2 + C2^2 + Cn^2 / N ]^1/2
kinetic theory equation
pV=1/3Nm(crms)^2
mole
one mole of a substance consisting of identical particles is the quantity of substance that contains N particles of the substance
molar mass
the mass of one mole of a substance
ideal gas
a gas under conditions such that it obeys boyle’s law
pressure law
for a fixed mass of an ideal gas at constant volume, its pressure is directly proportional to its absolute temperature
kinetic energy
the energy of moving object due to its motion. for an object of mass m moving at speed v, it kinetic energy.
Ek = 1/2 mv^2
kinetic energy of the molecules of an ideal gas
mean kinetic energy of a molecule of an ideal gas = 3/2KT
total kinetic energy of n moles of an ideal gas = 3/2 nRT
kinetic theory of a gas
gas consists of identical point molecules which do not attract another
random motion
collided elastically
pV= 1/3 Nm (Crms)^2
kinetic theory of gas equation
pV= 1/3 Nm (Crms)^2
Pv = 1/3 Nmc^2
P= pressure on the side of the box V = volume of the molecules in the box N = number of particles in the box M = mass of one particle C^2 = mean square speed
Random motion
When molecules are in a state of random motion they have a range of speeds and have no preferred direction of movement
Quality of a liquid and gas as described by kinetic energy
State the assumptions used in the derivation pv= 1/3Nmc^2
Elastic collision Intermolecular forces are negligible Volume of molecules negligible All molecules identical Newtons laws of motion apply
Describe how the motion of gas molecules can be used ti explain the pressure exerted by a gas on the walls of the container
Molecules are in constant random motion. When the molecules collide the walls exert a force on the molecules causing a change in momentum. The molecules exerts an force on the walls creating pressure
what happens if the temperature of gas is increased
molecules move faster
root mean square increases
distribution curve becomes flatter and broader
work done
pV
average molecular kinetic energy
1/2 m(Crms)^2 = 3/2 KT = 3RT / 2N
