gen chem 2 test 1 Flashcards
Thermodynamics
study of energy and its transformations
open system
system can transfer heat and vapor= mass and energy exchange
closed system
system can transfer heat= energy exchange
Isolated system
system has no transfer or exchange
ΔE is negative when…
energy is released, exothermic, reactants > products
ΔE is positive when…
energy is absorbed, endothermic, reactants < products
____ E is more stable than ____ E
low; high
heat capacity
C- amount of heat required to raise sample 1C or 1K; J/C J/K
molar heat capacity
Cmolar- amount of heat required to raise 1 mole 1C or 1K; J/mol * K
specific heat capacity
s- amount of heat required to raise 1 gram 1C or 1K; J/g * K
heat
transfer of thermal energy btwn 2 bodies with different temperature
q=msΔT
when q>0 what is the reaction and does it raise or lower energy
endothermic; higher energy
when q<0 what is the reaction and does it raise or lower energy
exothermic; lower energy
when w<0 what happens and what is the action of system
expansion “by system” system on surrounding
when w>0 what happens and what is the action of system
compression “on system” surrounding on system
Enthalpy
the heat transfer at a constant pressure, equal to heat, but it is a state function
ΔHrxn=
ΔHproducts – ΔHreactants
ΔE= (both)
q+w
ΔH – PΔV
Hess’s Law
ΔH is the same whether the reaction happens in 1 or many steps therefore you can add/subtract/multiply/divide H just as you would manipulate a reaction equation
Standard enthalpy of formation (heat of formation)- ΔHfo
- Reference point for all enthalpy expressions
- Results when 1 mole of a compound is formed from its elements in their standard state
- Found in appendix B in textbook, use tables , pay attention to states of matter
- ΔHfo is ZERO for any element in standard state
