Gases Flashcards
(50 cards)
two factors that determine the state of a substance
- the forces holding the particles tother
- the kinetic energy of the particles
ionic forces
- intramolecuclar
- usually solid state
- NaCl
Polar (dipole-dipole) forces
- intermolecular
- can be anything, usually liquid or gas
- HCL (g)
Dispersion force
- intermolecular
- liquid or gas
- CO2 (g)
What is the kinetic molecular theory?
all substances contain entities that are in constant motion
3 types of entity motion
- vibrational
- rotational
- translational
what particles have a vibration motion?
all particles
what particles have a rotational motion?
- liquids
- solids
- some solids
what particles have a translational motion?
- only in liquids and gases
temperature definition
a measure of the average kinetic energy of the entities of a substance
What is the kinetic molecular theory?
- the volume of an individual gas moecule is negligible
- there are no attractive nor repulsive forces between gas molecules
- gas molecules move randomly in all directions, in straight lines
- when gas molecules collide, they don’t loose kinetic energy
- ideal gases, do not condense into liquids when cooled
- the average kinetic energy of a gas molecule is directly related to the temperature. The greater the temperature, the greater the average motion of the molecules and the greater their kinetic energy
KMT describes a hypothetical gas called an ideal gas
i deal particles take up hardly any space
Who came up with kinetic molecular theory?
Robet Brown
pressure definition
the force exerted on an object per unit of surface area (P = F/A)
common SI unit of measurement of pressure
the pascal Pa = 1N/m^2
how is the pressure of a gas determined
by the kinetic moition
what device is used to measure pressure
a barometer
Describe the mercury barometer
- a closed tube is filled with mercury, then inverted into a pan
- gravity pulls the mercury downwards, but pressure pushes on the mercury in the pan, keeping it inside the tube
- the result is that we can measure the height of the Hg( mm) in the tube as a measure of pressure
mass of atmosphere
5.1 * 10^18 kg
= 1000 kg over an area of 1 m^2
Why is there lower pressure the higher up in the atmosphere you are?
there is lass atmosphere above, less atmosphere pushing down
what is atmospheric pressure
the force exerted on Earth’s surface by a column of air over a given area (101 325 N/m^2). Pressure is exerted equally in all directions
standard pressure and pressure at sea level
101.325 kPa
One atmosphere = ________kPa
101.325
STP
Standard Temperature and Pressure
at 0 degrees celsius and 101.325 kPa