Flashcards
What are the 5 assumptions made for an ideal gas (VVETE)??
- There are lots and lots of particles with random velocities.
- The individual particles have much smaller volumes than the volume of the gas.
- The collisions with container walls are perfectly elastic.
- The duration of collisions is much smaller than the duration of not-collisions.
- The electrostatic forces are negligible expect for during collisions.
Why is the assumption that collisions between particles and container walls being perfectly elastic useful??
Because it means no kinetic energy is lost.
If a particle hits a container wall at $u \text{ms}^{-1}$, what will its velocity be afterwards??
$$ -u \text{ms}^{-1} $$
If a particle of mass $m$ goes from $u \text{ms}^{-1}$ to $-u \text{ms}^{-1}$, what is the total change in momentum??
$$ -2mu $$
2021-11-18
What relationship is there between the pressure and temperature of a gas??
$$ \frac{\text{pressure}}{\text{temperature}} = \text{constant} $$
What relationship is there between the pressure and volume of a gas??
$$ \text{pressure} \times \text{volume} = \text{constant} $$
What relationship is there between the pressure, volume and temperature of a gas??
$$ \frac{\text{pressure} \times \text{volume}}{\text{temperature}} = \text{constant} $$
What equation links pressure, volume, moles and temperature of a gas??
$$ PV = nRT $$
What is the approximate value of $R$, the molar gas constant??
$$ 8.31 \text{J}\text{K}^{-1}\text{mol}^{-1} $$
2021-12-01
What practical can you do to measure absolute zero??
Plot a line of pressure against temperature and extrapolate backwards.
In words, how can you calculate the r.m.s. speed (root mean square speed)??
Square all the speeds, calculate the mean and then take the square root.
What is the symbol for the r.m.s. speed??
$$ \bar{c^2} $$
What is always going to be the mean velocity of the particles in a gas??
$$ 0\text{ms}^{-1} $$
How can you find the mean speed of gas particles??
Use the absolute values of the velocities for each particle, which won’t be zero.
What does the Maxwell-Boltzmann distribution show??
How many particles are moving at a given speed.
What does this show??
The Maxwell-Boltzmann distribution.
What’s another way of saying “most probable speed”??
Modal speed.
What happens to the Maxwell-Boltzmann distribution as it is heated??
It flattens and the peak shifts to the right.
What happens to the Maxwell-Boltzmann distribution as it is cooled??
It narrows and the peak shifts to the left.
What is the equation for pressure and volume of a gas in terms of the r.m.s. $\bar{c^2}$??
$$ pV = \frac{1}{3}Nm\bar{c^2} $$
$$pV = \frac{1}{3}Nm\bar{c^2}$$ In this equation, what does $N$ represent??
The number of particles in the gas.
$$pV = \frac{1}{3}Nm\bar{c^2}$$ How is this $N$ different from the one in $nRT$??
$n$ is the number of moles, $N$ is the number of particles.
2021-12-05
How can you calculate the Boltzmann constant $k$??
$$ k = \frac{R}{N_A} = \frac{8.31}{6.02\times 10^{23}} $$
What do you get if you substitute the Boltzmann constant into $pV = nRT$??
$$ pV = NkT $$
What two equations can you combine to relate the mean kinetic energy and temperature of a gas??
$$ pV = \frac{1}{3}Nm\bar{c^2} $$
and
$$ pV = NkT $$
What is the mean kinetic energy and temperature equation??
$$ \frac{1}{2} m\bar{c^2} = \frac{3}{2} kT $$
What is the formula for the kinetic energy of a gas at $T$ degrees kelvin??
$$ \frac{3}{2}kT $$
What is true about all gas atoms and molecules at a given temperature??
They have the same mean kinetic energy.
Backlinks
Metadata
date: 2021-11-09 16:32
tags:
- '@?public'
- '@?school'
- '@?physics'
- '@?year-2'
title: Physics - Ideal Gases
