# {Year 2} Chapter 4 - Thermal Physics (Up to page 74) Flashcards

What is the equation for internal energy?

U = Sum kinetic + sum potential, definition: ‘the sum of the randomly distributed kinetic and potential energies of the particles in a body’

What is the first law of thermodynamics?

The increase in internal energy of a system is equal to the heat added to the system minus the work done by the system, or deltaU = deltaQ - deltaW

What happens when a gas expands at a constant temperature?

It does work on its surroundings that can be calculated using the equation deltaW = pressure x deltaVolume

What is the letter for specific heat capacity and what is it?

c, specific heat capacity is the amount of energy is joules required to heat one kilogram of a substance one degree kelvin higher

What does the equation Q = ml mean?

Q is the amount of energy required to change a substance’s state without changing its temperature, m is mass, and l is specific latent heat

What is absolute zero?

The point at which no particles move, and thus there is no heat. Marked as 0 on the Kelvin scale, it is also equivalent to -273.15 degrees C. It is the lowest temperature possible

What is Boyle’s Law?

For a fixed mass of ideal gas at a constant temperature, the pressure of the gas is inversely proportional to its volume, aka p1 x v1 = p2 x v2

What is Amonton’s Law?

The pressure of a fixed mass and a fixed volume of gas is directly proportional to the absolute temperature of the gas

What are the three constants and their symbols?

Boltzman Constant (k), Avogadro’s Constant (N subscriptA) and the molar gas constant (R)

What is the main difference in how the gas laws and kinetic theory came to be recognised?

The gas laws were empirically found and based whereas kinetic theory is more theory based

What does the equation pV = nRT mean?

p = pressure, V = volume, n = moles, R = molar gas constant, NOT AVO’S CONSTANT, T = temperature

Name 3 assumptions made with an ideal gas.

Molecules are all identical, small, hard and spherical // Volume of the molecules is much less than that of the container // All the collisions between the particles are elastic and and all motion is frictionless // The molecules obey Newton’s Laws // The average distance between the molecules is much less than the size of them // They are constantly moving with Brownian motion (randomly) with a distribution of velocities around a mean // There are no attractive or opposing intermolecular forces other than when the particles collide // The time spent between collisions is much greater than the time spent colliding // there are no long range forces acting on the particles