Chapter 14 - Thermal Physics Flashcards
Define triple point.
The triple point of a substance is where the three phases of matter exist in thermal equilibrium, where there is no net transfer of thermal energy between phases.
What is the triple point of the water?
The triple point of water is 0.01°C and 0.61 kPa.
Define temperature.
Temperature is a measure of the “hotness” of an object on a chosen scale.
What is the zeroth law of thermodynamics?
The zeroth law states that if two objects are each in thermal equilibrium with a third, then all three are in thermal equilibrium with each other, meaning they are all at the same temperature.
Define the absolute temperature scale (or thermodynamic temperature scale).
The absolute temperature scale (or thermodynamic temperature scale) uses the triple point of pure water and absolute zero as its fixed points.
What is absolute zero?
Absolute zero is -273.16°C.
Using the kinetic model, state how Solids are structured.
Kinetic Model of Solids:
- Particles arranged in a regular 3-dimensional structure.
- Strong forces of attraction between the particles.
- Particles vibrate in their fixed positions.
Using the kinetic model, state how Liquids are structured.
Kinetic Model of Liquids:
- Particles are free to move around, without structure.
- Particles have a flowing motion.
- No fixed shape.
- Still forces of attraction between particles.
Using the kinetic model, state how Gases are structured.
Kinetic Model of Gases:
- Particles are far apart.
- Almost no forces of attraction between Particles.
- Particles move at high speed.
- Occupies much larger volume than other phases of matter.
- Collisions of particles with container is what creates pressure.
Define Brownian Motion.
Brownian Motion is the phenomena which demonstrates the existence of atoms and molecules. It was discovered in 1827 when Robert Brown discovered that pollen grains in water move haphazardly due to the collisions between the pollen grains and the water molecules.
Define Internal Energy.
The internal energy of a substance is defined as:
The sum of the randomly distributed kinetic and potential energies of atoms or molecules within the substance.
What are the electrostatic potential energy characteristics of a substance at different phases?
In different phases, the atoms or molecules of a substance have different electrostatic potential energies:
- Gas: The electrostatic potential energy is zero, because there are negligible electrical forces between atoms or molecules.
- Liquid: The electrostatic forces between atoms or molecules give the electrostatic potential energy a negative value, meaning energy must be supplied to break the atomic or molecular bonds.
- Solid: The electrostatic forces between atoms or molecules are very large, so the electrostatic potential energy has a large negative value.
Define the specific Heat Capacity Equation.
The specific heat capacity of a substance is defined as the energy required per unit mass to change the temperature by 1K or 1°C and has units of J kg⁻¹ K⁻¹.
c = E ÷ ( m x ∆θ )
Specific Heat Capacity = Energy ÷( mass x change in temperature )
J kg⁻¹ K⁻¹ = J ÷(kg x ∆°C)
What is the Specific Heat Capacity of water?
The specific Heat Capacity of Water is 4200 J kg⁻¹ K⁻¹.
Define Specific Latent Heat.
The specific latent heat of a substance is defined as the energy required to change the phase per unit mass while at constant temperature.
L = E ÷M
Latent Heat = Energy ÷Mass
J Kg⁻¹ = J ÷Kg
