A2 Physics Ideal Gases

For an ideal gas several assumptions are made about the particles including

• they collide elastically with each other and the container wall

• they experience significant intermolecular forces

• the volume they occupy as individual particles is insignificant compared to the volume of the container

• there are a very large number of particles inside the container

An ideal gas has a density of 2.0 kgm^-3 at a pressure of 2.2 x 10⁵ Pa and a temperature of 295 K. Calculate the mean square speed of the gas atoms.

• 330 kms^-1

• 110 000 ms^-1

• 373 ms^-1

• 19 ms^-1

In the equation of state for an ideal gas pV = nRT

• n = number of particles in the gas

• p = pressure of the gas

• R = the molar gas constant 8.31 JK^-1mol^-1

• T = temperature in degrees celcius

This is the

• root mean square speed

• mean square speed

• mean square root speed

• squared root mean speed

Rewriting the equation of state gives : pV = NkT

where:

• N = the number of moles x 6.022 x 10²³

• V = volume occupied by the gas

• T = temperature in degrees celsius

• k = 1.38 x 10^-2 JK^-1

Given the equation E_k = 3/2 kT, calculate the temperature of Helium atoms that are able to leave the atmosphere with a speed of 1.1 x 10⁴ms^-1. The mass of an individual Helium atom is 6.6 x 10^-27kg. (k = 1.38x10^-23)

• 1.9 x 10⁴ K

• 1.9 x 10^{3 o} C

• 1.5 x 10² K

• 200 K

The mean square speed of atoms of Neon gas at 273 K with density 0.900 kgm^-3 is 3.4 x 10⁵ ms^-1. Calculate the r.m.s. of the same gas at 546 K.

• 820 ms^-1

• 680 000 ms^-1

• 240 ms^-1

• 340 000 ms^-1

For an ideal gas at constant temperature and density ρ what effect would doubling the density have on the mean square speed?

• none

• mean square speed would double

• mean square speed would halve

• mean square speed would quadruple

For an ideal gas at constant temperature and pressure p at volume V, what affect would halving the pressure have on the volume?

• volume would double

• volume would halve

• volume would triple

• none

For an ideal gas trapped inside a container of fixed volume, which of these statements is true?

• all particles are moving rapidly and randomly

• particles exchange momentum with the wall over very short time frames

• all particles are moving idly and haphazardly

• the particle volume accounts for most of the space in the container