chem unit 6

adiabatic

a process that occurs without transfer of heat or matter between a thermodynamic system and its surroundings.

boiling point

the temperature in which the vapor pressure of the liquid is equal to external or atmospheric pressure.

calorie

the amount of energy needed to raise the temperature of one gram of water by one degree Celsius.

calorimetry

experimental determination of the enthalpy changes of reactions.

celcius

a temperature scale defined by the freezing and boiling points of pure water as 0 o C and 100 o C.

change of state

a substance going from solid to liquid, liquid to gas or the reverse of those processes.

condensation

the movement of molecules from the gas phase to the liquid phase.

dietary calorie

a unit used to determine the amount of energy in foods which is equal to 1 kilocalorie.

endothermic

a thermodynamic process in which heat flows into the system from the surroundings.

energy

the capacity to do work and transfer heat.

enthalpy

the amount of heat energy gained or lost by a process at constant pressure.

enthalpy of fusion

the heat energy required to convert a solid to a liquid at the melting point.

enthalpy of a solution

the amount of heat gained or lost in the process of solution formation.

enthalpy of vaporization

the amount of heat energy required to convert a liquid to gas at the boiling point.

entropy

the measure of the degree of randomness and disorder in the system.

exothermic

a thermodynamic process in which heat flows from the system to the surroundings.

fahrenheit

a temperature scale defined by the freezing point and boiling point of pure water to be 32 o F and 212 o F.

first law of thermodynamics

the total energy in the universe is constant.

fusion

the state change from solid to liquid.

hess’s law

Heat evolved in a reaction can be calculated by adding heats measured from other reactions (sum of all enthalpy changes).

internal energy

the sum of the potential and kinetic energies of particles in a system.

isothermal

a change of a system in which the temperature remains constant.

joule

the SI unit of energy.

kelvin

a temperature scale in which the units are the same size as Celsius degrees but the zero point is the lowest possible temperature or absolute zero.

kilocalorie

a unit of energy equivalent to 1000 calories.

kilojoule

a unit of energy equal to 1000 Joules.

kinetic molecular theory

all matter is made up of a large number of small particles that are in constant random motion.

law of conservation of energy

the overall energy in the universe is constant.

melting point

the temperature at which the crystal lattice of a solid collapses and the solid starts to convert to liquid.

second law of thermodynamics

the overall entropy of the universe increases with every spontaneous reaction.

specific heat capacity

the quantity of heat necessary to change the temperature of 1 gram of any substance by 1 o C or 1 K.

standard enthalpy of a reaction

the enthalpy change that occurs from a reaction with all reactants and products in their standard states.

standard molar enthalpy of formation

the enthalpy change for the formation of 1 mole of a compound directly from its elements in their standard states.

standard state

the most stable form of an element or compound in the physical state at 1 bar of pressure and a specified temperature.

sublimation

the direct conversion of a solid to a gas with no liquid phase.

surroundings

everything outside of the system in a thermodynamic process.

system

the collection of objects or substances being evaluated in a thermodynamic process.

temperature

a physical property that determines the direction of heat flow in an object or a measure of its average kinetic energy.

thermal equilibrium

a condition in which the system and surroundings are at the same temperature and heat transfer stops.

thermodynamics

the science of heat and work.

triple point

the temperature and pressure at which the solid, liquid and gas phases of a substance are in equilibrium.

vaporization

the state change from a liquid to a gas.

volatility

the tendency of the molecules of a liquid to escape into the gas phase.

work

quantity of energy transferred by a force acting through a distance.