Conditions & Equations Flashcards
Isothermal Conditions=?
No change in temperature
Heat (q) can still change!
∆U=0 only if it is an ideal gas
Isolated System
No exchange of matter with the surroundings
No exchange of energy with the surroundings
Closed System
No exchange of matter with the surroundings
Exchanges energy with the surroundings
Open System
Exchanges matter with the surroundings
Exchanges energy with the surroudnings
Equation for Non-Expansion Work?
w=mgh
Work:
General Equation?
Conditions for Equation?
W= -∫PexdV
system must be reversible
Heat:
General Equation?
Conditions for Equation?
q= ∫CdT
Process must be reversible
Note: C=constant, so q=CΔT
Internal Energy:
General Equation?
ΔU= q + W
Equation for Work at constant pressure?
W= -PΔV
Equation for ΔU when volume is constant?
ΔU= qv = CvΔT
Enthalpy:
General Equation
Equation @ constant pressure
Equation @ constant volume
ΔH= ΔU + Δ(PV)
ΔH= qp
ΔH= ΔU + VΔP
aH2O(l) —> aH2O(l) at constant pressure
Equation For:
q
w
ΔU
ΔH
qp= nCp,m(Tf-Ti)
w=0 (because change in V is negligible)
ΔU= nCp,m(Tf-Ti)
ΔH= ΔU
Note: ΔH=ΔU=qp
aH2O(l) —> aH2O(l) at constant volume
Equation For:
q
w
ΔU
ΔH
qv= Cv,mn(Tf-Ti)
w=0
ΔH = ΔU = qv
aH2O(l) —> aH2O(l) at constant Temperature
Equation For:
q
w
ΔU
ΔH
q=0
w=0 (because change in V is negligible)
ΔU=0
ΔH=0
Adiabatic Conditions
No exchange of heat with the surroundings
Temperature can still change!
q=0
aH2O(g) —> aH2O(g) at constant pressure
Equation For:
q
w
ΔU
ΔH
qp= nCp,m(Tf-Ti)
w= -nR(Tf-Ti)
ΔU= nCv,m(Tf-Ti)
ΔH= nCp,m(Tf-Ti)
Note: Cp,m=Cv,m+R
aH2O(g) —> aH2O(g) at constant volume
Equation For:
q
w
ΔU
ΔH
qv= nCv,m(Tf-Ti)
w=0
ΔU=qv
ΔH= n(Cv,m+R)(Tf-Ti)
aH2O(g) —> aH2O(g) at constant temperature
Equation For:
q
w
ΔU
ΔH
q= -w= nRT ln(Vf / Vi)
w= -nRT ln(Vf / Vi)
ΔU=0
ΔH=0
Note: if given P instead of V, then w= -nRT ln(Pi / Pf)
Phase Transitions:
aH2O(l) —> aH2O(g) at constant T & P
What is:
w
q
∆U
∆H
w= -P (V(g) - V(l))
qp=∆Htransition (can be ∆Hvap , ∆Hfus , etc)
∆Hp=qp
∆U= ∆H - PV(g)
Steps of the Carnot Cycle
1) Isothermal expansion
2) Adiabatic expansion
3) Isothermal compression
4) Adiabatic compression
Note: all state functions (for the whole process) are 0 because it’s a cycle
Carnot Cycle
Total Work Equation?
Total Heat Equation?
Wtotal= -nRThot ln(V2/V1) - nRTcold ln(V4/V3)
qtotal = nRThot ln(V2/V1) + nRTcold ln(V4/V3)
General Equation for Entropy?
∆S=∫ dqrev/T
Equation for Efficiency?
E= w / qhot
E= (qh + qc) / qh
or
E= 1 + qc /qh
or
E= 1 - Tc / Th
-for carnot cycle
Gibbs free energy equation?
∆G= ∆H - T∆S
∆Suniverse= -∆Gsystem / T
