Process calculation and Thermodynamics quiz 2019

 

PROCESS CALCULATIONS AND THERMODYNAMICS QUIZ 2019

Q. 1 Consider a sealed rigid bottle containing CO₂ and H₂O at 10 bar and ambient temperature. Assume that the gas phase in the bottle is pure CO₂ and follows the ideal gas law. The liquid phase in the bottle contains CO₂ dissolved in H₂O and is an ideal solution. The Henry’s constant at the system pressure and temperature is H_CO2 =1000 bar . The equilibrium mole fraction of CO₂ dissolved in H₂O is ____(rounded off to three decimal places).

Q. 2.For a single component system, vapor (subscript g) and liquid (subscript f) coexist in mechanical, thermal and phase equilibrium when

u_g = u_f (equality of specific internal energy)
h_g = h_f (equality of specific enthalpy)
s_g = s_f (equality of specific entropy)
g_g = g_f (equality of specific Gibbs free energy)

Q. 3 Consider a rigid, perfectly insulated, container partitioned into two unequal parts by a thin membrane (see figure). One part contains one mole of an ideal gas at pressure P_i and temperature T_i while the other part is evacuated. The membrane ruptures, the gas fills the entire volume and the equilibrium pressure is P_f = P_i/4. If C_p (molar specific heat capacity at constant pressure), C_v (molar specific heat capacity at constant volume) and R (universal gas constant) have the same units as molar entropy, the change in molar entropy (S_f - S_i) is

C_p ln2 + Rln4
-C_v ln2 + Rln4
Rln4
C_p ln2

Q. 4 For a binary nonideal A-B mixture exhibiting a minimum boiling azeotrope, the activity coefficients, γ_i (i = A, B), must satisfy

γ_A >1,γ_B >1
γ_A <1,γ_B >1
γ_A =1,γ_B =1
γ_A <1,γ_B <1

Q. 5 Carbon monoxide (CO) reacts with hydrogen sulphide (H₂S) at a constant temperature of 800 K and a constant pressure of 2 bar as:
CO + H₂S ↔ COS + H₂
The Gibbs free energy of the reaction ∆g⁰_rxn = 22972.3 J / mol and universal gas constant R = 8.314 J / (mol K). Both the reactants and products can be assumed to be ideal gases. If initially only 4 mol of H₂S and 1 mol of CO are present, the extent of the reaction (in mol) at equilibrium is...............(rounded off to two decimal places).

Q. 6 Consider a vessel containing steam at 180 °C. The initial steam quality is 0.5 and the initial volume of the vessel is 1 m³. The vessel loses heat at a constant rate q under isobaric conditions so that the quality of steam reduces to 0.1 after 10 hours. The thermodynamic properties of water at 180 °C are (subscript g: vapor phase; subscript f: liquid phase):
specific volume : v_g = 0.19405 m³ / kg, v_f = 0.001127 m³ / kg
specific internal energy : u_g = 2583.7 kJ / kg, u_f = 762.08 kJ / kg
specific enthalpy : h_g = 22778.2 kJ / kg, h_f = 763.21 kJ / kg
The rate of heat loss q (in kJ/hour) is............(rounded off to the nearest integer).

Q. 7 For a given binary system at constant temperature and pressure, the molar volume (in m³ mol) is given by: u = 30 x_A + 20 x_B + x_A x_B(15x_A - 7x_B), where x_A and x_B are the mole fractions of components A and B, respectively. The volume change of mixing ∆u (in m³/mol) at x_A = 0.5 is..................(rounded off to one decimal place).

Q. 8 A fractionator recovers 95 mol% n-propane as the distillate from an equimolar mixture of npropane and n-butane. The condensate is a saturated liquid at 55 ⁰C. The Antoine equation is of the form, ; and the constants are provided below:

Assuming Raoult’s law, the condenser pressure (in bar) is ___________ (rounded of to one decimal place)