THERMODYNAMICS IN 1001 Flashcards
Which of the following are intensive properties?
I. temperature
II. pressure
III. composition
IV. mass
(A) I only
(B) IV only
(C) I and II
(D) I, II, and III
(D) I, II, and III
How many independent properties are required to completely fix the equilibrium state of a pure gaseous compound?
2
Which of the following thermodynamic relations is INCORRECT?
(A) TdS = dU + pdV
(B) TdS = dH - Vdp
(C) U = Q - W
(D) H = U + pV
C. because it is U = Q + W
Which of the following relationships define enthalpy?
(A) h = u + P/T
(B) h = u + pv
(C) h = u + p/v
(D) h = pv + T
(B) h = u + pv
Which of the following is true for water at a reference temperature where enthalpy is zero?
(A) Internal energy is negative
(B) Entropy is nonzero
(C) Specific volume is zero
(D) Vapor pressure is zero
(A) Internal energy is negative
In an ideal gas mixture of constituents i and j, what is the mole fraction of component i, xᵢ, equal to?
(A) Tᵢ / (Tᵢ + Tⱼ)
(B) Zᵢ / (Zᵢ + Zⱼ)
(C) pᵢ / (pᵢ + pⱼ)
(D) mᵢ / (mᵢ + mⱼ)
(C) pᵢ / (pᵢ + pⱼ) where p is the partial pressure
The compressibility factor, Z, is used for predicting the behavior of nonideal gases. How is the compressibility factor defined relative to an ideal gas? (Subscript “c” refers to critical value.)
(A) Z = p / pc
(B) Z = pV / RT
(C) Z = T / Tc
(D) Z = (T / Tc) (pc / p)
(B) Z = pV / RT
On what plane is the Mollier diagram plotted?
(A) p-V
(B) p-T
(C) h-s
(D) s-u
(C) h-s (enthalpy and entropy, respectively)
How is the quality, x, of a liquid-vapor mixture defined?
(A) the fraction of the total volume that is saturated vapor
(B) the fraction of the total volume that is saturated liquid
(C) the fraction of the total mass that is saturated vapor
(D) the fraction of the total mass that is saturated liquid
(C) the fraction of the total mass that is saturated vapor
What is the expression for the heat of vaporization?
hg = enthalpy of the saturated vapor
hf = enthalpy of the saturated liquid
(A) hg + hf
(B) hf - hg
(C) hg - hf
(D) h²g - h²f
(C) hg - hf
The first law of thermodynamics is based on which of the following principles?
(A) conservation of mass
(B) the enthalpy-entropy relationship
(C) action-reaction
(D) conservation of energy
(D) conservation of energy
The general energy equation for an open system involves the following five terms.
I. accumulation of energy
II. net energy transfer by work (standard sign convention)
III. net energy transfer by heat (standard sign convention)
IV. transfer of energy in by mass flow
V. transfer of energy out by mass flow
Using the standard sign conventions, what is the proper arrangement of these terms for the general energy equation satisfying the first law of thermodynamics?
(A) I = -II + III + IV - V
(B) I = II + III + IV + V
(C) I = II + III + IV - V
(D) I = II - III - IV + V
(A) I = -II + III + IV - V
What is the value of the work done for a closed, reversible, isometric system?
Zero
The expansion of a gas through a plug at a high pressure results in a temperature rise, while at lower pressures a temperature drop occurs. The Joule-Thompson coefficient μᴊᴛ, is defined as the ratio of the change in temperature to the change in pressure. The temperature at which μᴊᴛ changes from positive to negative is called the inversion temperature. When μᴊᴛ is negative, which of the following statements is true?
(A) Gases may be liquified by pressurization.
(B) No liquification is possible.
(C) Only trace liquification is possible
(D) Liquification can be obtained only with a catalyst
(A) Gases may be liquified by pressurization.
How does an adiabatic process compare to an isentropic process?
(A) adiabatic: heat transfer = 0; isentropic: heat transfer ≠ 0
(B) adiabatic: heat transfer ≠ 0; isentropic: heat transfer = 0
(C) adiabatic: reversible; isentropic: not reversible
(D) both: heat transfer = 0; isentropic: reversible
(D) both: heat transfer = 0; isentropic: reversible
What is true about the polytropic exponent, n, for a perfect gas undergoing an isobaric process?
(A) n > 0
(B) n < 0
(C) n ➡ ∞
(D) n = 0
(D) n = 0
During an adiabatic, internally reversible process, what is true about the change in entropy?
(A) It is always zero.
(B) It is always less than zero.
(C) It is always greater than zero.
(D) It is infinite.
(A) It is always zero.
For an irreversible process, what is true about the total change in entropy of the system and surroundings?
(A) dS = ∞
(B) dS = 0
(C) dS > 0
(D) dS < 0
(C) dS > 0
For which type of process is the equation dQ = TdS valid?
(A) irreversible
(B) isothermal
(C) reversible
(D) isobaric
(C) reversible
Which of the following is true for any process?
(A) ΔSsurroundings + ΔSsystem ≥ 0
(B) ΔSsurroundings + ΔSsystem ≤ 0
(C) ΔSsurroundings + ΔSsystem < 0
(D) ΔSsurroundings + ΔSsystem > 0
(A) ΔSsurroundings + ΔSsystem ≥ 0
What is the equation for the work done by a constant temperature system?
(A) W = mRT ln(V₂ - V₁)
(B) W = mR(T₂ - T₁) ln(V₂ / V₁)
(C) W = mRT ln(V₂ / V₁)
(D) W = mRT ln(p₂ / p₁)
(C) W = mRT ln(V₂ / V₁)
