EnerqetICS
4. ENDOTHERMIC AND EXOTHERMI, 4.2 ENTHALPY, 4.3 MEASURING
are
ploce, chemcol bonds breale and new ones
When a chemical reaction reacion lakcs
formed. Bond breakings uses Cnerqy making bonds eleases eneryy
combustion, neutralis otion
Exothem - ene as qiven out. eg Lhermal decomposticn
Endothemc energy takenn in the ceverse
exothermicn one direction, t w be endotherm(
a ceactionIs
fuels, which hawe very exothemic
lhemochemistry enables us to compare effiueny f kJmoL.
ceactions when combusted. Enthalpy s measured n
Enthalpy changes
Enthalp chanqe - heat changc at constoat pcessurepressure, 248| temperature
100LPa
Standa conditONS for woeasuing AH-
Ln an exotheCmc reaction, AH 1s negatue
endo thecmi reaction, DH s posutave
af substances affect eathalpy
State sybais are impatast - state
ENTHALPy
ENTHALPY
R - AH
REACTION PROGRESS
REACTON PROGRESS
level diagram for an
Enthalpy level diaaram for
Eathalpy
endother mic reactian
exothernic reactian
mole of a substance is formed trom ts
when one
DH - enthalpy chane with adreactants cnd prsdcts
standard conditions
(onstituent elenents under
n ther standard states
a substane is conpletely burned
mole of
enthalpy cnange when one reactants and products their
with all
urygen under stondard conditions,
standad states
4. ENDOTHERMIC AND EXOTHERMI, 4.2 ENTHALPY, 4.3 MEASURING
are
ploce, chemcol bonds breale and new ones
When a chemical reaction reacion lakcs
formed. Bond breakings uses Cnerqy making bonds eleases eneryy
combustion, neutralis otion
Exothem - ene as qiven out. eg Lhermal decomposticn
Endothemc energy takenn in the ceverse
exothermicn one direction, t w be endotherm(
a ceactionIs
fuels, which hawe very exothemic
lhemochemistry enables us to compare effiueny f kJmoL.
ceactions when combusted. Enthalpy s measured n
Enthalpy changes
Enthalp chanqe - heat changc at constoat pcessurepressure, 248| temperature
100LPa
Standa conditONS for woeasuing AH-
Ln an exotheCmc reaction, AH 1s negatue
endo thecmi reaction, DH s posutave
af substances affect eathalpy
State sybais are impatast - state
ENTHALPy
ENTHALPY
R - AH
REACTION PROGRESS
REACTON PROGRESS
level diagram for an
Enthalpy level diaaram for
Eathalpy
endother mic reactian
exothernic reactian
mole of a substance is formed trom ts
when one
DH - enthalpy chane with adreactants cnd prsdcts
standard conditions
(onstituent elenents under
n ther standard states
a substane is conpletely burned
mole of
enthalpy cnange when one reactants and products their
with all
urygen under stondard conditions,
standad states
