Sections

Glossary
# Glossary

- absolute zero
- the lowest possible temperature; the temperature at which all molecular motion ceases

- Avogadro’s number
- ${N}_{\text{A}}$ , the number of molecules or atoms in one mole of a substance; ${N}_{\text{A}}=6\text{.}\text{02}\phantom{\rule{0.25em}{0ex}}\times \phantom{\rule{0.25em}{0ex}}{\text{10}}^{\text{23}}$ particles/mole

- Boltzmann constant
- $k$ , a physical constant that relates energy to temperature; $k=\text{1.38}\phantom{\rule{0.25em}{0ex}}\times \phantom{\rule{0.25em}{0ex}}{\text{10}}^{\text{\u201323}}\phantom{\rule{0.25em}{0ex}}\text{J/K}$

- Celsius scale
- temperature scale in which the freezing point of water is $0\phantom{\rule{0.25em}{0ex}}\text{\xba}\text{C}$ and the boiling point of water is $\text{100}\phantom{\rule{0.25em}{0ex}}\text{\xba}\text{C}$

- coefficient of linear expansion
- $\alpha $, the change in length, per unit length, per $1\phantom{\rule{0.25em}{0ex}}\text{\xba}\text{C}$ change in temperature; a constant used in the calculation of linear expansion; the coefficient of linear expansion depends on the material and to some degree on the temperature of the material

- coefficient of volume expansion
- $\beta $, the change in volume, per unit volume, per $1\phantom{\rule{0.25em}{0ex}}\text{\xba}\text{C}$ change in temperature

- critical point
- the temperature above which a liquid cannot exist

- critical pressure
- the minimum pressure needed for a liquid to exist at the critical temperature

- critical temperature
- the temperature above which a liquid cannot exist

- Dalton’s law of partial pressures
- the physical law that states that the total pressure of a gas is the sum of partial pressures of the component gases

- degree Celsius
- unit on the Celsius temperature scale

- degree Fahrenheit
- unit on the Fahrenheit temperature scale

- dew point
- the temperature at which relative humidity is 100 percent; the temperature at which water starts to condense out of the air

- Fahrenheit scale
- temperature scale in which the freezing point of water is $\text{32}\phantom{\rule{0.25em}{0ex}}\text{\xba}\text{F}$ and the boiling point of water is $\text{212}\phantom{\rule{0.25em}{0ex}}\text{\xba}\text{F}$

- ideal gas law
- the physical law that relates the pressure and volume of a gas to the number of gas molecules or number of moles of gas and the temperature of the gas

- Kelvin scale
- temperature scale in which zero K is the lowest possible temperature, representing absolute zero

- mole
- the quantity of a substance whose mass—in grams—is equal to its molecular mass

- partial pressure
- the pressure a gas would create if it occupied the total volume of space available

- percent relative humidity
- the ratio of vapor density to saturation vapor density

- phase diagram
- a graph of pressure vs. temperature of a particular substance, showing at which pressures and temperatures the three phases of the substance occur

*PV*diagram- a graph of pressure vs. volume

- relative humidity
- the amount of water in the air relative to the maximum amount the air can hold

- saturation
- the condition of 100 percent relative humidity

- sublimation
- the phase change from solid to gas

- temperature
- the quantity measured by a thermometer

- thermal energy
- $\overline{\text{KE}}$, the average translational kinetic energy of a molecule

- thermal equilibrium
- the condition in which heat no longer flows between two objects that are in contact; the two objects have the same temperature

- thermal expansion
- the change in size or volume of an object with change in temperature

- thermal stress
- stress caused by thermal expansion or contraction

- triple point
- the pressure and temperature at which a substance exists in equilibrium as a solid, liquid, and gas

- vapor
- a gas at a temperature below the boiling temperature

- vapor pressure
- the pressure at which a gas coexists with its solid or liquid phase

- zeroth law of thermodynamics
- law that states that if two objects are in thermal equilibrium, and a third object is in thermal equilibrium with one of those objects, it is also in thermal equilibrium with the other object