Flashcards in Thermal physics Deck (47)
a measure of the average kinetic energy of the particles in a system
the flow of thermal energy
Define thermal equilibrium
when two objects are at the same temperature so there is no flow of heat.
What causes pressure?
The collisions between gas particles and the inside walls of the container
What are the properties of an ideal gas
1. Molecules move with random motion, 2. Molecules obey Newton’s laws, 2. Molecules have same average kinetic energy, 3. There are no attractive forces between molecules, 4. Collisions between molecules are elastic, 5. Molecules are point masses (have zero volume), 6. Time taken between collisions is much greater than during collisions.
Describe Brownian motion
particles moving randomly due to collisions with many other small, fast particles.
State the third law of thermodynamics
the entropy of an ideal substance will be zero at absolute zero (0K).
What is Avogadro’s constant?
The number of atoms in exactly 12g of carbon-12 (6.02x1023)
What is the specific latent heat of fusion?
The energy needed to change the state a substance from solid to liquid without a change of temperature.
What is the specific latent heat of vaporisation?
The energy needed to change the state a substance from liquid to gas without a change of temperature.
Based on observation or experience rather than theory or pure fact.
What is meant by the term elastic collisions?
Both KE and momentum are conserved and total E is constant before and after the collision
Define absolute scale
Measured in K starting at absolute zero
Particles exert pressure on the wall of a container because…
Molecules have momentum
Momentum change at wall
Momentum change at wall leads to force
Why is average velocity in a container zero?
Velocity is a vector
a chemical process where a solid becomes a gas without going through a liquid stage