Physics 13: Temperature, Kinetic Theory, & the Gas Laws Flashcards
Heat transfer
movement of heat energy from one place or material to another
Temperature
what we measure with a thermometer
Celsius
temperature scale in which water freezes at 0 and boils at 100
Degrees Celsius
unit of the Celsius temperature scale
Fahrenheit
most frequently used temp scale in the US; freezing point is 32; boiling point is 212
Degrees Fahrenheit
unit of the Fahrenheit temperature scale
Kelvin
temperature scale commonly used in science; absolute; 0 in this scale is the lowest possible temp
Absolute Zero
lowest possible temperature; temp at which there is no molecular motion
Thermal Equilibrium
heat flows from the hotter object to the cooler object until they have exactly the same temp
Zeroth Law of Thermodynamics
If 2 systems, A & B, are in thermal equilibrium with each other, & B is in thermal equilibrium with a 3rd system, C, then A is also in thermal equilibrium with C
Thermal Expansion
change in size or volume of a given mass with temperature
Coefficient of Linear Expansion
alpha, the change in length, per unit length, per 1 degree Celsius change in temp; a constant; depends on the material and to some degree on the temp of the material
Coefficient of Volume Expansion
Beta; almost exactly equal to 3 alpha; change in volume, per unit volume, per 1 degree Celsius change in temp
Thermal Stress
created by thermal expansion or contraction; can be destructive or useful
Ideal Gas Law
PV=NkT; P = absolute pressure of a gas; V is the volume it occupies; N is the # of atoms and molecules in the gas; T is its absolute temp (K)
Boltzmann Constant
k; =1.38 x 10^-23 J/K
Avogadro’s Number
the actual number of atoms or molecules in 1 mole; = 6.02 x 10^23 mol^-1
Thermal Energy
average translational kinetic energy of a molecule (KE); = 1/2mv^2 = 3/2kT
PV Diagram
graph of pressure versus volume
Critical Point
critical temp above which a liquid cannot exist
Critical Pressure
minimum pressure needed for liquid to exist at the critical temp
Phase Diagrams
PT graphs; there are well-defined regions on these graphs that correspond to various phases of matter
Sublimation
the phase change from solid to gas
Triple Point
all 3 curves on the phase diagram meet at this single point, where all 3 phases exist in equilibrium
Vapor Pressure
Pressure at which a gas coexists with its solid or liquid phase; created by faster molecules that break away from the liquid or solid and enter the gas phase; depends on both the substance and its temperature; increase in temp increases it
Partial Pressure
the pressure a gas would create if it occupied the total volume available
Dalton’s Law of Partial Pressure
in a mixture of gases, the total pressure is the sum of partial pressures of the component gases
Relative Humidity
tells us how much water vapor is in the air compared with the maximum possible
Saturation
maximum humidity (100%); evaporation is inhibited
Dew Point
relative humidity is 100%; fog may result from the condensation of water droplets if they are small enough to stay in suspension
Percent Relative Humidity
ratio of vapor density to saturation vapor density; = vapor density/saturation vapor density x 100%
