Chapter 14 - Thermal Physics Flashcards
Describe thermal equilibrium.
Objects are in thermal equilibrium when there is no net flow of energy between them.
What is the absolute scale of temperature?
A scale of measuring temperature that uses absolute zero and the triple point of water as its fixed points.
What is the triple point of a substance?
A specific temperature where the three phases of matter exist in thermal equilibrium.
Describe the structure of a solid.
-Strong forces between particles.
-Vibrate in fixed positions.
-Regular 3D structure, packed closely together.
Describe the structure of a liquid.
-Particles are free to move around.
-No fixed shape.
-Particles are still close together.
Describe the structure of a gas.
-Particles are far apart.
-Move at random speeds & directions.
-Almost no forces of attraction.
-Occupies a large volume compared to liquids.
-Collide with each other & container.
What is Brownian motion?
The continuous motion of small particles suspended in a fluid.
Define the internal energy of a substance.
The sum of a substance’s kinetic and potential energies.
Define absolute zero.
The lowest possible temperature, at which substances have minimum internal energy.
What happens when you increase a substance’s temperature?
Its molecules move faster.
What happens to a substance when it changes phase?
Temperature does not change, but electrostatic potential energy increases significantly.
Define specific heat capacity.
The energy required per unit mass to heat a substance by 1 Kelvin.
Define specific latent heat.
The energy required per unit mass for a substance to change phase while at constant temperature.
What is the difference between specific latent heat of fusion and specific latent heat of vaporisation?
Fusion is solid to liquid; vaporisation is liquid to gas.
How do you convert from ℃ to Kelvin?
T(K) ≈ θ + 273℃
Describe an experiment you could use to demonstrate Brownian motion.
-Put smoke in a glass cell and shine a beam of light on it.
-Use a microscope to view the moving smoke particles.
How does Brownian motion support the theory of the random movement of particles?
Particles continuously and randomly change directions as if they were colliding with other particles.
Outline an experiment to determine a liquid’s specific heat capacity.
-Heat the liquid in an insulated container by a known temperature.
-Calculate c using E=mcΔθ.
