20.2 Flashcards
(27 cards)
what do molecules in a gas move with
random speed in random directions
what is the pressure of a gas on a surface due to
gas molecules hitting the surface
each impact causes a tiny force on the surface
because there are large numbers of impacts each second the overall result is that the gas exerts a measurbale pressure on the surface
what are elastic collisions
when gas molecules collide with each other or a surface it bounces of without losing speed because no energy is lost
molecules have negligible volume and are too small to see normally how can you see there effect
if you observe smoke particles with a microscope
if light is directed throught the smoke you will see the smoke particles moving unpredictibly
what is the random motion of particles known as
the Brownian motion after Robert Brown who first obserevd it in 1827 with pollen grains in water
why is the motion of the particle random
because it is bombarded unevnely and randomly by individual molecules adn therefore experiences forces due to these impacts which change its magnitude and direction at random
what did brownain motion show
the existance of molecules and atoms
what was avogadros hypothesis
that equal volumes of gases at the same temperature and pressure contain an equal number of molecules
what is Na defined as
the number of atoms in exactly 12g of carbon isotope 12C6
what is the value of Na
6.023x10^23
how do you find the mass of an atom
mass of the substance / Na
what is one atomic mass unit
1/12th of mass of carbon therefore
1.661x10^-27
what is one mole of a substance consisting of identical particles defined as
The quantity of a substance that contains Na particles
what the number of moles in a given quantity of substance
its molarity
what is the unit of molarity
mol
what is the molar mass of substance
the mass of 1 mol of the substance
what is the unit of molar mass
kgmol^-1
example, the molar mass of oxygen is 0.032kgmol
0.032kg of oxygen gas contains Na oxygen molecules
how do you find the number of moles in a substance
mass / molar mass
How to find the number of molecules in a substance
Na x Ms/M
for when it contains
what can the three experimental gas laws be combined to create
pV/T = Constant for a fixed mass of ideal gas
how was the molar gas constant found
for equal volumes of gases at the same temp and pressure contain equal numbers of moles
an ideal gas at 273K 101Kpa and 0.0224m^3. For any one mole is equal to 8.31mol^-1K^-1
whats the value of the molar gas constant (R)
8.31mol^-1K^-1
what is the gradient of the graph pV against T for n moles where the line goes throguh absolute 0
the gradient is nR
Number of moles x R
