What is the relationship between pressure and motion of molecules in a gas?

Question

Is the relationship between pressure (cause) and motion of molecules in a gas (effect) inverse or direct?

Answer 1

Assuming that all other quantities (volume, number of molecules) are constant, an increase in pressure causes an increase in temperature, therefore there is a direct relationship between the pressure of a gas and the movement of its molecules.

Further proof: PV = nRT, if V, n, and R are constant, then P = kT.

Adios from University of Waterloo

Answer 2

I don't have my books with me, but it goes something like that. The energy of a given particle is given by:

mv^2/2.

where m is the mass of a particle and v it's speed.

Now, if you take more advanced studies, you'll learn that the energy of a particle that can move in 3 dimension is given by its temperature

E= 3kT/2

where k is the Boltzmann constant and T the temperature in K.

I won't get in the maths here, but if you do the average of all the particles in your gas that can hit a certain wall (and thus creating a pressure), you'll find that

PV= nkT

where P is the pressure, V the volume and n the number of particles.

As you can see, nkT= nm^2/2 and P depends directly on the speed of the particles in it.

Now, if you increase the pressure, you will increase the energy of the particles inside of it. You can say it goes both ways.

Drummer: You are right. I was assuming that the temperature T remained the same during compression for my explanation.

Answer 3

pressure formula is

p= F/A

where;
p is pressure
F is force
A is area of contact

so it means that the pressure depends on the force acting on the area... if a force acting on small area, the pressure will be greater and vice-versa

so, the relationship for molecules in a gas, molecules in gas will flow from place with high pressure to lower pressure ...take for example, when we were breathing... when we inhale, our lungs volume increased, review back to formula P=F/A , the area is greater, so, the pressure is lower than the air surrounding us,that's why air will be sucked into our lungs....

Answer 4

compressing a gas causes the gas to lose energy(molecular kinetic energy, aka temperature) but release that energy into the surrounding system as heat, and when a gas is decompressed the molecules gain energy from the surrounding system making it colder.
this can be seen with a can of compressed air when you spray it th can will get very cold, and if you were to toss it in a fire it would explode because the high energy in molecules would cause the gas to expand.

hope that helps

Answer 5

Their relationship is VP=nRT T=thermodynamic temperature, P=pressure, V=volume of gases, n=number of mole of gases, R=ideal gas constant (SI: 8.3145 J/(mol K)) *The law works with any consistent set of units, provided that the temperature scale is zero at absolute zero, and the proper gas constant is used.

Answer 6

direct cos the molecules are closer in higher pressure states and the more pressureised they get the hotter they get and so they vibrate more