Exam 1 Flashcards
First law of thermodynamics
energy can be converted from one form to another with the interaction of heat, work, and internal energy, but cannot be created or destroyed
Second law of thermodynamics
total entropy in spontaneous processes increases irreversibly
Third law of thermodynamics
entropy of perfectly crystalline substance at 0 K is 0
What did Clausius say about the second law of thermodynamics?
no process is possible whose sole result is the transfer of heat from a cold body to a hot body
What is the critical point? (2)
the point on a phase diagram at which the liquid and gas phases have the same density and are therefore indistinguishable; in the P-V plot, the critical point is an inflection point in the constant temperature line write out partial derivatives
What is a supercritical fluid?
A phase of matter that forms at a temperature/pressure above the critical point that effuses like a gas and dissolves substances like a liquid
Define extensive quantity.
Quantity that depends on the size of a system
Give three examples of extensive quantities.
volume, mass, energy
Define intensive quantity.
Quantity that doesn’t depend on the size of a system
Give three examples of intensive quantities.
pressure, temperature, density
Write out the equation for pressure.
write out - Chapter 16: Textbook Notes
Write out the equation for the compressibility factor.
write out - Chapter 16: Textbook Notes
Write out the van der Waals equation.
write out
What do the variables a and b in the van der Waals equation correspond to?
a - corresponds to intermolecular attractions; b - corresponds to the size of the molecules
When does Z = 1?
Z = 1 under all conditions for ideal gases
When does Z not equal 1?
Z does not equal 1 as pressure increases (deviations from ideal gas behavior)
Write out the van der Waals equation in cubic form.
write out - Chapter 16: Textbook Notes
Define heat.
manner of energy transfer that results from a temperature difference between the system and its surroundings.
Heat input is a
positive quantity
Heat evolved is a
negative quantity
Define work.
the transfer of energy between the system of interest and its surroundings as a result of the existence of unbalanced forces between the two
Work done on the system is a (sketch figure)
sketch - Dineli’s Exam 4 Notes, page 6; positive quantity - compression
Work done by the system is a (sketch figure)
sketch - Dineli’s Exam 4 Notes, page 6; negative quantity - expansion
What is the equation for pressure-volume work at constant pressure?
write out - Chapter 19: Textbook Notes
What is the equation for pressure-volume work at not-constant pressure?
write out - Chapter 19: Textbook Notes
Define state function.
a property that depends only upon the state of the system, and not upon how the system was brought to that state.
(T/F) Energy is a state function.
True - write out - Chapter 19: Textbook Notes
Isothermal compression requires what work?
the minimum amount of work
Isothermal expansion requires what work?
the maximum amount of work
Write out the equation for isothermal/reversible work.
write out - Chapter 19: Textbook Notes (page 2)
(T/F) Work is a state function.
False, it is a path function.
What is the relationship between work, heat, and energy?
∆U = q + w
What is the second statement of the first law of thermodynamics?
the sum of work and heat, which are both inexact differentials, is a state function and an exact differential
Define adiabatic process.
process in which no energy as heat is transferred (q = 0)
Write out the three derivation equations for constant-volume heat capacity.
write out - Chapter 19: Textbook Notes (page 2)
What is the value of C(V) for one mole of a monatomic ideal gas?
3/2*R
What is the value of C(V) for one mole of a nonlinear polyatomic ideal gas?
3R
Under what conditions is enthalpy relevant?
constant-pressure situations
What are the relationships between q, ∆H, ∆U, P, and ∆V?
(1) qp = ∆H; (2) ∆H = ∆U + P∆V
What is the law of corresponding states?
all fluids, when evaluated at the same reduced temperature + pressure, have roughly the same Z value and thus deviate from ideal gas behavior to the same degree
For an ideal gas, internal energy (U) only depends on
temperature
What is the Joule-Thomson coefficient?
mu(sub)JT and is equivalent to (di-T/di-P) at constant H
Nonzero values of the Joule-Thomson coefficient reflect
intermolecular interactions
How did Clausius sum up the first two laws of thermodynamics?
The energy of the universe is constant, the entropy tending to a maximum
Convert 1 atm-L into joules
1 atm-L = 101.33 J
Define a state function.
Independent of the path taken, to establish a property or value
Give four examples of a state function.
S, G, H, T
Give two examples of a path function.
w, q
Write out the van der Waals equation of state in the PV=nRT form.
write out - Dineli’s Exam 4 Review, page 1
Calculate dP/dV using explicit differentiation.
calculate - Dineli’s Exam 4 Review, page 1
Calculate dP/dV using implicit differentiation.
calculate - Dineli’s Exam 4 Review, page 2
What is the Zeroth Law of Thermodynamics?
if 2 thermodynamic systems are in equilibrium with a third, then the first two are in equilibrium with each other (A=C, B=C, then A=B)
What is Dalton’s Law of Partial Pressure?
if we have a mixture of ideal gases, the total pressure of the mixture is equal to the sum of the partial pressures of the component gasses
What is the Equipartition Theorem?
At thermal equilibrium, each microscopic degree of freedom of a molecule has an average energy 1/2kbT
What is the internal energy of a monatomic ideal gas containing N particles?
U = 3/2 * N * kb * T; U(bar) = 3/2 * R * T; because R = kb * NA
Define reversible process.
When Pext and P differ only infinitesimally, the process is called reversible because the process could be reversed by decreasing the external pressure infinitesimally
Define irreversible process.
When Pext is controlled to be constant and the final pressure; expansion/compression is allowed to continue until the gas re-equilibrates at the final pressure and volume
Sketch a pressure-volume plot for isothermal reversible compression.
sketch - Dineli’s Exam 4 Review, page 8
Sketch a pressure-volume plot for isothermal reversible expansion.
sketch - Dineli’s Exam 4 Review, page 8
What happens to pressure and temperature in adiabatic compression?
pressure and temperature both increase without any gain or loss of heat
What happens to pressure and temperature in adiabatic expansion?
pressure and temperature both decrease without any gain or loss of heat
What is the difference between state and path functions in terms of differentials?
state functions are exact differentials, whereas path functions are inexact differentials
What did the Joule-Thomson experiment try to do?
tried to measure the temperature change when a gas expanded in a vacuum
In the microscopic entropy equation, what does W represent?
the number of microstates
Sketch out the microscopic representation of entropy and the associated table.
sketch/write out Dineli’s Exam 4 Review, page 15
Define microstate.
number of different possible arrangements of molecular position at a particular thermodynamic state
What is the relationship between microstates and entropy?
more microstates mean more entropy
Write out the two formulas associated with the Clausius inequality.
write out Dineli’s Exam 4 Review, page 17
In the Clausius Inequality, when does the equality sign apply and when does the inequality sign apply?
equality sign applies if change is carried out reversibly (i.e. system is in equilibrium during process); inequality is applied if change is carried out irreversibly at any stage
The Clausius Inequality as a statement is equivalent to
the Second Law of Thermodynamics
Write out the formula for the entropy of a gaseous mixture.
write out - Formulas to Memorize, page 1
