Ch 14 - Gases Flashcards
Atmosphere
A layer of gases surrounding a planet that is retained by gravity
Two competing factors that determine the thickness of the atmosphere
Kinetic energy of gas molecules
Pull of the planet’s gravity
The balance between the two competing factors that setermine the thickness of the atmosphere is called
Hydrostatic Balance
the hydrostatic balance is the ____ of the atmosphere.
the edge of the atmosphere
Atmospheric pressure
Is the force per unit area caused by the weight of air.
Units: Pa or N/m2
Atmospheric pressure in not _____
Not uniform
Atmospheric pressure measuments are used to
Are used to predict weather conditions.
Barometer
A barometer is a device that measures atmospheric pressure.
The Barometer consists of a mercury tube upside down in a dish filled with mercury.
What does the height of the Mercury show?
The height of the mercury column in the tube tells the atmospheric pressure.***
The principle of the barometer:
*Mercury column exerts pressure on the mercury in the dish.
*Atmosphere exerts pressure on the mercury in the dish.
*These two pressures must be equal so that the atmospheric pressure supports the mercury column.
Boyle’s Law
The pressure and volume of an enclosed gas are inversely proportional
If you increase pressure, the volume will decrease by the same factor.
Ex If pressure is doubled, volume will halve.
Buoyancy in Air
An object surrounded by air is buoyed up by a force equal to the weight of the air displaced.
Archimedes’ principle applies to air and liquids, since they are both fl
A gas-filled balloon will continue to rise until
*the weight of displaced air equalsthe total weight of the balloon.
*Or until thebuoyant force on the balloonequals its weight.
When the weight of air displaced by an object is ________ than the weight of the object,
it ____.
greater, rises
When the weight of air displaced by an object _____ the weight of the object, it _____ in air.
equals, hovers
