Chem Subject Test 1 And 2 "thermochemistry"

Front 1

first of thermodynamics

Back 1

expression of the universal law of conservation of energy, and identifies heat transfer as a form of energy transfer.

The increase in the internal energy of a thermodynamic system is equal to the amount of heat energy added to the system minus the work done by the system on the surroundings.

dU = Q-W

du = inc in the internal enery of system

by James Prescott Joule

Front 2

endothermic

Back 2

absorb heat from warmer sys to cooler system

Front 3

exothermic

Back 3

release heat from warmer sys to cooler system

Front 4

heat

Back 4

q= mcT(f-i)

c=specific heat

measured in the same unit as energy
(calories or joules)

Front 5

entropy (S)

Back 5

measure of the disorder or randomness of a system

greater the disorder = inc in entropy

state function
Dealta S = Sfinal - Sinitial

Front 6

entropy btw phases

Back 6

gas>liquid>solid

Front 7

delta S (state function)

Back 7

dealta S = q/T

q = heat added to a sys

Front 8

Second law of thermodynamics

Back 8

all spontaneous processesin an isolated system lead to inc in entropy

Front 9

delta S universe

Back 9

= delta Ssys + delta Ssurrounding >0

Front 10

Enthalpy (H)

Back 10

heat content of a system

heat change at constant P

Front 11

delta H

Back 11

= Activation E foward - activation E reverse

=Eproduct -Ereactant

=Hproduct-Hreactant

equal to the heat absorbed or evolved by the systme at constant P

Front 12

delta H = +

Back 12

endothermic

Front 13

delta H = -

Back 13

exothermic

Front 14

standard heat of formation

delta Hf

Back 14

at STP (1atm, 273K)

Front 15

standard head of rxn

Back 15

the hypotheical enthalpy change that would occur if the exn were carried out under standard conditions

=(sum of del Hf of product) -
(sum of del Hf of reactant)

Front 16

Hess law

Back 16

states that if rxn can be broken down into a series of steps the enthahpy change for the overall net reaction is just the sum of the enthalpies ofeach step

Front 17

bond dissociation energy

Back 17

average of the engergy required to break a particular type of bond in one mole of gaseous molecules

deltal H rxn =
(H of vond broken)+(H of bonds formed

or = energy input - energy output

Front 18

Gibbs Free Energy (G)

Back 18

=dH-TdS
describe overall spontaneity of a exn

represents maximum energy of enery released by a process occuring at STP

Front 19

dG = -

Back 19

rxn is spontaneous

Front 20

dG = +

Back 20

rxn is not spontaneous

Front 21

dG = 0

Back 21

equalibrium

and dH=TdS

Front 22

dH = -
dS = +

Back 22

spontaneous at all temp

Front 23

dH = +
dS = -

Back 23

nonspontaneous at all temp

Front 24

dH = +
dS = +

Back 24

spontaneous only at high temp

Front 25

dH = -
dS = -

Back 25

spontaneous at low temp

Front 26

dGrxn

Back 26

= (sum of dGf of product)-
(sum of dGf of reactant)

Front 27

conduction

Back 27

heat transfered directly through vibration of atoms and molecule of materials

Front 28

radiation

Back 28

E transfered via electromagnetic waves

no medium, occur in vaccum

Front 29

convection

Back 29

transfered by the bulk movement of fluids, known as convection current

warm air rise and cool air falls due to difference in density

Front 30

when system can't exchange energy or matter with the surrounding as with an insulated bomb reactor

Back 30

isolated system

Front 31

when system cannot exchange energy but not matter with the surrounding, as with steam radiator

Back 31

closed system

Front 32

when syste can exchange both matter and energy with the surrounding as with pot of boiling water

Back 32

open system

Front 33

isothermal

Back 33

constant temp

Front 34

adiabatic

Back 34

no heat exchange occur

Front 35

isobaric

Back 35

pressure of the system remains constant