# Thermochemistry Terms- Tyler IDe

energy

the capacity to do work or to produce heat

temperature

reflects the random motions of the particles in a particular substance

heat

involves the transfer of energy between two objects due to a temperature difference

work

force acting over a distance

system

the part of the universe we are focusing on

surroundings

everything else in the universe

exothermic

energy flows out

endothermic

energy flows in

internal energy

the sum of the kinetic and potential energies of all the particles in the system

change in internal energy formula

deltaE=q+w

q when endothermic

q is positive

q when energy flows out

q is negative

example of work done by a gas

expansion

example of work done to a gas

compression

work formula

w=-PdeltaV

enthalpy formula

H=E+PV

change in enthalpy

deltaH

at constant pressure, the relationship between deltaH and q, or energy flow as heat

deltaH=q

heat of reaction aka

change in enthalpy aka

enthalpy change formula

deltaH=Hproducts - Hreactants

specific heat capacity

the energy required to raise the temperature of one gram of a substance by one degree celsius

molar heat capacity

the energy required to raise the temperature of one mole of a substance by one degree celsius

calorimeter

a device used to determine the heat associated with a chemical reaction

heat capacity formula

heat absorbed/increase in temperature

specific heat capacity of water

4.184J/g?C

q (energy released by the reaction) formula

m(deltaT)Cs

extensive property

depends on the amount of substance present

intensive property

not dependent on the amount of substance present

at constant volume...

deltaE=q+w=q

standard enthalpy of formation

the change in enthalpy that accompanies the formation of one mole of a compound from its elements in their natural states at standard conditions

Hess's law

if an overall reaction can be written as the sum of several reactions, the overall enthalpy equals the sum of the individual enthalpies

Van der Waal's equation

(Pobserved + a(n/V)�)x(V-nb)=nRT

in Van der Waal equation, a...

accounts for the attractive forces

in Van der Waal equation, b...

accounts for actual volume instead of neglibible volume