For an ideal gas undergoing adiabatic compression, the entropy change is:
A Positive B Negative C Zero D Indeterminate without volume ratio
For a reversible adiabatic process, dq = 0, therefore ΔS = ∫dq_rev/T = 0. Entropy remains constant during reversible adiabatic processes.
In a constant pressure process, the heat absorbed by a system equals:
A Change in internal energy only B Enthalpy change C Work done by the system D Change in entropy
At constant pressure, q_p = ΔH (change in enthalpy). This is the definition of enthalpy and is a key relationship in engineering thermodynamics.
For a binary ideal solution, the total vapor pressure at constant T is given by:
A P = P₁°x₁ + P₂°x₂ (Raoult's law) B P = P₁°/x₁ + P₂°/x₂ C P = (P₁° + P₂°)/(x₁ + x₂) D P = P₁° + P₂° regardless of composition
Raoult's law states P_i = P_i°x_i for ideal solutions. Total pressure P = P₁°x₁ + P₂°x₂. This assumes ideal mixing behavior.
During a constant volume process, the first law of thermodynamics simplifies to:
A ΔU = q + w = q - PΔV B ΔU = q (since w = 0 at constant volume) C ΔU = w (since q = 0 in all processes) D ΔU = 0 (no energy change)
At constant volume, ΔV = 0, so w = -P∫dV = 0. Therefore, ΔU = q + w = q + 0 = q. All heat goes into internal energy change.
A gas undergoes an isothermal expansion from 2 L to 5 L at 298 K. If the process is reversible, what is the sign of entropy change for an ideal gas?
A Positive B Negative C Zero D Cannot be determined
For isothermal expansion of an ideal gas, ΔS = nR ln(V_f/V_i) = nR ln(2 5
In the van der Waals equation, the term 'a' represents:
A Volume correction due to molecular size B Pressure correction due to intermolecular attractive forces C Temperature correction factor D Compressibility factor at critical point
In (P + a/V²)(V - b) = RT, 'a' corrects for intermolecular forces reducing pressure, while 'b' corrects for molecular volume.
What is the Clausius-Clapeyron equation used for?
A Calculating work done in cyclic processes B Relating vapor pressure to temperature during phase transitions C Determining heat capacity of substances D Calculating entropy of mixing
Clausius-Clapeyron equation: ln(P₂/P₁) = -(ΔH_vap/R)(1/T₂ - 1/T₁) describes phase equilibrium.
For a system at equilibrium, the chemical potential of a substance in different phases must be:
A Equal B Different C Zero D Proportional to temperature
At phase equilibrium, μ_liquid = μ_vapor = μ_solid. This equality determines equilibrium conditions.
What does the Gibbs free energy criterion ΔG < 0 indicate for a process?
A Process is non-spontaneous at all temperatures B Process is spontaneous and irreversible C Process is at equilibrium D Process releases maximum useful work
ΔG < 0 indicates spontaneous, irreversible process under constant T and P conditions.
A system absorbs 500 J of heat and does 300 J of work. The change in internal energy is:
A 200 J B 800 J C -200 J D 500 J
First law: ΔU = Q - W = 500 - 300 = 200 J (using convention W = work by system).
