B.1 Thermal energy transfers Flashcards
Solid Phase Properties
Fixed volume, do not flow, particles in regular rows, little energy, vibrate around fixed positions, strong intermolecular forces
Liquid Phase Properties
Can flow and take the shape of their container, random particle arrangement, more energy than solids, particles move around each other, weaker intermolecular forces than solids
Gas Phase Properties
Fill their container, volume changes with pressure/temperature, particles far apart and random, high energy and move quickly, largest thermal expansion.
Thermal Expansion in Phases
Upon heating, particles gain energy and move apart, weakening intermolecular forces. Solids expand the least, gases the most, and liquids are intermediate.
Density Definition
Mass per unit volume of a substance. Higher density means particles are closer together. Calculated using ρ = m/V, with ρ in kg/m³.
Celsius Scale
Measures temperature with 0°C as the freezing point and 100°C as the boiling point of water. Commonly used for everyday temperature measurements.
Kelvin Scale
Absolute temperature scale with 0 K as absolute zero, the point at which particles have minimum kinetic energy. 0°C equals 273.15 K.
Absolute Zero
The lowest possible temperature, 0 K or -273.15°C, where the particles of a substance have minimal kinetic energy.
Conversion from Celsius to Kelvin
Add 273.15 to the Celsius temperature to convert to Kelvin. For example, 25°C + 273.15 = 298.15 K.
Relationship between Temperature and Kinetic Energy
In the Kelvin scale, temperature is directly proportional to the average kinetic energy of the particles of a substance.
Specific Heat Capacity (c)
The amount of energy required to raise the temperature of 1 kg of a substance by 1 K. It indicates a material’s ability to store thermal energy.
Phase Change
A transition of matter from one state (solid, liquid, gas) to another without changing temperature. It involves energy changes affecting particle interaction but not kinetic energy.
Latent Heat
The energy absorbed or released during a phase change. It does not increase temperature but changes the state of a substance (fusion for melting, vaporization for boiling)
Heating Curve
A graph showing how a substance’s temperature changes with energy input, highlighting plateaus during phase changes where temperature remains constant despite energy addition.
Calculating Energy for Temperature Change
Q is energy, m is mass, c is specific heat capacity, and ΔT is temperature change.
Conduction
The transfer of thermal energy through direct contact between particles. More efficient in solids due to close particle arrangement.
Convection
The transfer of heat in fluids (liquids or gases) by the movement of heated particles, creating convection currents
Thermal Radiation
Transfer of energy by electromagnetic waves. It does not require a medium, thus can occur in a vacuum.
Conductors vs. Insulators
Conductors allow easy thermal energy transfer (e.g., metals), while insulators resist it (e.g., wood, air).
Fourier’s Law of Heat Conduction
The rate of heat transfer through a material is directly proportional to the temperature difference and the material’s thermal conductivity, inversely proportional to the material’s thickness.
Black Body Definition
An idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence, and emits radiation at a rate described by Planck’s law.
Wien’s Displacement Law
The peak wavelength of the emission from a black body is inversely proportional to its temperature, allowing temperature determination from peak radiation wavelength.
Stefan-Boltzmann Law
The total energy radiated per unit surface area of a black body across all wavelengths is directly proportional to the fourth power of the black body’s absolute temperature.
Luminosity of a Black Body
The total amount of energy emitted by a black body per unit time, dependent on its surface area and the fourth power of its temperature.
Apparent Brightness
The observed brightness of a star or celestial object as seen from Earth, depending on the object’s luminosity and its distance from the observer.
