Chapter 15 - Ideal Gases Flashcards
Define one mole.
6.02x10²³ (Avogadro’s constant) particles of a substance.
What is meant by the phrase ‘ideal gas’?
A gas that obeys the three gas laws, Boyle’s Law, The Pressure Law and Charles’ Law.
State Boyle’s Law
At a constant temperature, the pressure and volume of a gas are inversely proportional.
State the Pressure Law.
At a constant volume, the pressure of a gas is directly proportional to its absolute temperature.
State Charles’ Law.
At a constant pressure, the volume of a gas is directly proportional to its absolute temperature.
What do the letters R and n represent in the equation PV = nRT?
R = molar gas constant.
n = amount of gas in moles.
What do the letters N and k represent in the equation pV = NkT?
N = number of particles.
k = the Boltzman constant.
How do newton’s laws apply to the kinetic theory of gases?
-No forces between particles, so they move with constant velocity.
-When a particle collides with a wall, the wall exerts an equal and opposite force on the particle.
-The size of this force can be calculated with F = ma.
Explain pressure using the kinetic theory of gasses.
A large number of particles are constantly colliding with the container walls, exerting a steady force.
State the six assumptions of kinetic theory.
-The gas contains a large number of particles.
-Particles move rapidly and randomly.
-The volume of particles is negligible compared to the volume of the gas.
-Collisions are perfectly elastic.
-The duration of each collision is negligible.
-No forces between particles.
Why do we use root mean square speed?
The average velocities of particles in a gas would amount to 0, so r.m.s. speed is used to give the typical speed.
How do we work out the internal energy of an ideal gas particle?
Internal energy = kinetic energy. Potential energy is 0J because there are no forces between particles.
Outline an experiment to investigate Boyle’s Law.
-Use a pump to increase the pressure of a sealed tube of air.
-Measure the volume as pressure increases.
-Multiplying the values should give a constant.
Name an instrument used to measure pressure.
A Bourdon gauge.
Outline an experiment to investigate the Pressure Law.
-Submerge a flask of air in water.
-Heat the water, constantly measuring the temperature & pressure, until it boils.
How can the pressure law be used to determine absolute zero?
A graph of pressure against temperature crosses the x-axis at absolute zero.
