What Happens to gases when pressure increases and decreases?
967745
when pressure increases, temperature increases...when pressure decreases, temperature decreases.....Charles\n\nwhen pressure increases, volume decreases, when pressure decreases, volume increases...Boyles
567232
Under high pressure, the helium is liquified.  The tank is then attached to the pressurized tank and helium simply pours into the tank via gravity.  When the tank is opened, atmospheric pressure converts it back to gas.
897109
atmospheric pressure decreases as altitude increases.\n(think about gravity)\n\nan object that floats is less dense than the fluid it floats in.\n"A piece of the object weighs less than a piece of the fluid the same size."
782736
If ideal gas law is obeyed...\n\ndensity = mass/V == n/V\n\nPV = nRT\nP = (n/V)RT\n\nIf temp is held constant then increasing density increases pressure.
797306
Lets look at gas in a balloon.  Lets pretend we can see the gas molecules buzzing around on a micro-scale.  At the boundary of the gas and the surface there are always some of these molecules hitting the surface.  The molecules hitting the surface, much like you pushing on a surface, creates the pressure.  So, the faster the molecules are traveling (due to a rise in temperature) the harder they will impact the surface.  Also if there are more molecules present, more will be hitting the surface and also increase the pressure.  This can be verified by analyzing the ideal gas law, PV=nRT.  Where P=Pressure, n=amount of gas molecules, and T=temperature.  We can see if we raise the n or T the pressure must rise also, assuming a constant V(volume).\n\nOn a macro-scale, such as our atmosphere, the gas has a mass just like anything else.  Although the mass is small, there are miles of gas so the total mass has a noticeable affect here at the ground.  We don't notice the pressure because we are used to it (sometimes you may notice it when your ears 'pop' driving up or down a large hill) but the atmosphere is exerting pressure on everything.
908873
b\nThe concentration of the gas in the liquid is at equilibrium when the vapor pressure of the gas above the liquid equals the vapor pressure of the gas in the liquid.  Increasing the pressure above the liquid changes the equilibrium and  more gas is absorbed by the liquid.
317634
Pressure will increase if temperature increases, assuming that the container remains at a constant volume. Because the molecules are moving faster, they collide more often with the walls of the container, so the pressure goes up.\n\nThis is demonstrated by Gay-Lussac's Law, which states that that for a fixed amount of gas (fixed number of moles) at a fixed volume, the pressure is proportional to the temperature, so:  P/T = constant.\n\nIn case you need to know this for a test, and easy mnemonic  is "Pete and Tom are Gay" (Pressure and Temperature are proportional according to Gay-Lussac).
741092
When the atmosphere of an area heats up it expands, when it expands it occupies a larger volume than before, but the weight (mass) of this atmosphere is the same as when it was smaller, so it now it exerts less force per square area than when it was colder..so the pressure is lower, See formation of a hurricane. Hot air, causes low pressure, rises  and allows air from hi pressure area to rush in to equalize pressures
645900
Boyles Law PV/T I think. Anyway it has to do with the relationship of Pressure to Volume. If one increases the other decreases. Its useful in industry in making liquid Nitrogen and has endless applications in dealing with gasses in Chemisrty and Physics.
475777
All gases get denser as they cool. Air in a balloon would also deflate if it gets cold. The gas in the balloon would expand if the balloon got hot.  Not to get too complicated, but colder temperatures make the molecules of the gas get closer together, which makes the balloon shrink.
127151
Hot air has molecules which are more active from the energy that they receive from heat and, therefore, tend to collide more often with other molecules than when the air is cool. When more collisions occur, more pressure will be built up. To maintain pressure in the surroundings, the molecules will move to a place with less pressure, and that is upwards. When the air cools, it will go down again and the cycle continues.
751958
heat change\ncolor change\nemmission of gas
803179
Changes in air pressure and possibly humidity.  Your body turns into a barometer.
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as the temp goes up the molecules of gas move faster and collide more often with more energy into the balloon increaseing pressure and expanding the balloon.  As it cools the opposite happens.  Draw your own diagram!
818902
You better read something on this:\nhttp://en.wikipedia.org/wiki/Pressure
894173
Gases disperse to fill whatever container they occupy.   Gases are composed of matter and thus occupy space.  Since no two objects of matter can occupy the same space at the same time and a gas expands to occupy a given space a force(pressure) exist.  As the temperature increases the pressure increases because you are adding energy to the system.
126339
actually you should phrase it "why does pressure decrease when temperature is reduced?" because a rise or fall in temperature affects air pressure (not the other way around).  the higher temperature is, the faster molecules in the air are moving and therefore they increase the space they take up.  if temperature is lower, molecules move around less and require less space.