ch. 9 Flashcards
thermodynamics- energy
the capacity to do work or to produce heat
E
kinetic energy
energy of motion
KE=1/2mv^2
potential energy
stored energy
heat
q
energy transferred between two objects caused by a temperature difference between them
work
w
force acting over a distance
state function
a property that is independent of the pathway
1 joule
kg*m^2/s^2
meter second
1 cal
4.184 J
endothermic
system absorbs heat
heat flows into the system from the surroundings
exothermic
system evolves heat
heat flows out of system to surrounding
internal energy
E
delta E = q+w
change in internal energy
delta E <0
system losing energy
exothermic
delta E>0
system gains energy
endothermic
work equation
w=-Pext.deltaV
expansion
system/gas does work
w<0 negative work
compression
work done on the system
w>0 positive work
Enthalpy
H=E+PV
deltaH = q when the pressure is constant
ideal gases kinetic energy
3/2RT
molar heat capacity
energy required to raise temperature of 1 mole of a substance by 1K
c
molar heat capacity under certain conditions: when volume is constant
Cv=3/2R
molar heat capacity under certain conditins: constant pressure
Cp=Cv+R
= 5/2 R
delta E under constant pressure and volume
delta E = nCvdeltaT
n(3/2R)deltaT
delta H under constant presssure and volume
deltaH = nCpdeltaT
n(5/2R)deltaT
q(heat) under constant pressure
nCpdeltaT
n(5/2R)deltaT
q(heat) under constant volume
nCvdeltaT
n(3/2R)deltaT
work under constant pressure
-pext.deltaV
work under constant volume
0
specific heat capacity
c=q/mdeltaT
derived from q=mcdeltaT
calorimetry ; qsoln equation
qsoln = Csoln msoln deltaTsoln
calorimetry qrxn
qrxn=-qsoln
when looking at qrxn look at the question to see if it is negative or positive (depending on if exothermic or endothermic)
bomb calorimeter qrxn equation
qrxn=-CcaldeltaT
