Description : Specific __________ does not change during phase change at constant temperature and pressure. (A) Entropy (B) Gibbs energy (C) Internal energy (D) Enthalpy
Last Answer : (B) Gibbs energy
Description : Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.). (A) Entropy (B) Internal energy (C) Enthalpy (D) Gibbs free energy
Last Answer : (D) Gibbs free energy
Description : (∂H/∂T)P is the mathematical expression for (A) CV (B) Entropy change (C) Gibbs free energy (D) None of these
Last Answer : (D) None of these
Description : _________ does not change during phase transformation processes like sublimation, melting & vaporisation. (A) Entropy (B) Gibbs free energy (C) Internal energy (D) All (A), (B) & (C)
Last Answer : (B) Gibbs free energy
Description : The Gibbs free energy change of a reaction at `27^(@)C` is -26 Kcal. and its entropy change is -60 Cals/K. `Delta H` for the reaction is :-
Last Answer : The Gibbs free energy change of a reaction at `27^(@)C` is -26 Kcal. and its entropy change is -60 Cals/K. ... Cals. C. 34 K. Cals. D. `-24` K. Cals.
Description : If a reaction has an enthalpy of -54.32 kJ/mol and an entropy of -354.2 J/(K*mol), what is the Gibbs free Energy at 54.3(degrees c)?
Last Answer : DeltaG = DeltaH - TDeltaS dG = -54.32 kJ/mol - (54'32+273)K(-354.2J/molK) NB Thevtemperature is quoted in Kelvin(K) and the Entropy must be converted to kJ by dividing by '1000'/ Hence dG = ... 115.94 kJ/mol dG = (+)61.61 kJ/mol Since dG is positive, the reaction is NOT thermodynamically feasible.
Description : Gibbs free energy per mole for a pure substance is equal to the (A) Latent heat of vaporisation (B) Chemical potential (C) Molal boiling point (D) Heat capacity
Last Answer : (B) Chemical potential
Description : Melting of wax is accompanied with __________ in entropy. (A) Increase (B) Decrease (C) No change (D) None of these
Last Answer : (A) Increase
Description : If the heat of solution of an ideal gas in a liquid is negative, then its solubility at a given partial pressure varies with the temperature as (A) Solubility increases as temperature ... (D) Solubility increases or decreases with temperature depending on the Gibbs free energy change of solution
Last Answer : (B) Solubility increases as temperature decreases
Description : Pick out the wrong statement: (A) The capacity of an evaporator is reduced by the boiling point elevation (B) Corrosive liquid is normally passed through the tubes in a ... recompression evaporator (D) Heat sensitive materials should be concentrated in high pressure evaporators
Last Answer : (D) Heat sensitive materials should be concentrated in high pressure evaporators
Description : The actual temperature drop across the heating surface of an evaporator depends on the (A) Liquid depth over the heating surface (B) Solution being evaporated (C) Pressure difference between the steam chest and the vapor space above the boiling liquid (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Pick out the wrong statement about cavitation. (A) Sudden reduction of pressure in a fluid flow system caused by flow separation, vortex formation or abrupt closing of valve leads to cavitation ... (D) Large scale cavitation cannot damage pipeline, restrict fluid flow and damage steam turbine blades
Last Answer : (D) Large scale cavitation cannot damage pipeline, restrict fluid flow and damage steam turbine blades
Description : In which of the following reactions, standard reaction entropy change (S°) is positive and standard Gibb's energy change (G°) decreases sharply with increasing temperature? (1) 2 2 1 1 1 C graphite O (g) CO (g) 2 2 2 (2) 2 1 C ... CO(g) O (g) CO (g) 2 (4) 2 1 Mg(s) O (g) MgO(s) 2
Last Answer : C graphite O (g) CO(g)
Description : __________________ represents the highest pressure and highest temperature at which liquid and vapor can coexist in equilibrium. a) Critical Point b) Boiling Point c) Quality Point d) None of the above
Last Answer : Critical Point
Description : Pick out the wrong statement. (A) Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom (B) The heat capacity of solid inorganic substance is exactly equal to the ... isolated system (D) At absolute zero temperature, the heat capacity for many pure crystalline substances is zero
Last Answer : (C) There is an increase in entropy, when a spontaneous change occurs in an isolated system
Description : Specific/molar Gibbs free energy for a pure substance does not change during (A) Sublimation (B) Vaporisation (C) Melting (D) Either (A), (B) or (C)
Last Answer : (D) Either (A), (B) or (C)
Description : The molar excess Gibbs free energy, gE, for a binary liquid mixture at T and P is given by, (gE/RT) = A . x1. x2, where A is a constant. The corresponding equation for ln y1, where y1is the activity co-efficient of component 1, is (A) A . x22 (B) Ax1 (C) Ax2 (D) Ax12
Last Answer : (A) A . x22
Description : Leidenfrost point is a term concerned with the (A) Condensation of the saturated vapor on a cold surface (B) Concentration of a corrosive solution by evaporation (C) Heat transfer between two highly viscous liquids (D) Boiling of a liquid on a hot surface
Last Answer : (D) Boiling of a liquid on a hot surface
Description : In an operating distillation column, the (A) Vapors and liquids are at their dew point and bubble point respectively (B) Driving force for the liquid flow is its specific weight (C) Driving force for ... bottom to the top of the column (D) Highest temperature is encountered at the top of the column
Last Answer : (C) Driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column
Description : The increasing vapor pressure caused by heating a liquid is due to------? A. increase inter-molecular interactions B. increasing potential energy of molecules C. increasing kinetic energy of molecules (Answer) D. decreasing surface tension
Last Answer : C. increasing kinetic energy of molecules (Answer)
Description : Gibbs-Duhem equation (A) States that n1dμ1 + n2dμ2 + ....njdμj = 0, for a system of definite composition at constant temperature and pressure (B) Applies only to binary systems (C) Finds no application in gas-liquid equilibria involved in distillation (D) None of these
Last Answer : (A) States that n1dμ1 + n2dμ2 + ....njdμj = 0, for a system of definite composition at constant temperature and pressure
Description : Gibbs-Duhem equation relates composition in liquid phase and the __________ at constant temperature & pressure. (A) Fugacity (B) Partial pressure (C) Activity co-efficient (D) All (A), (B), and (C)
Last Answer : (D) All (A), (B), and (C)
Description : Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature. (A) Infinity (B) Minus infinity (C) Zero (D) None of these
Last Answer : (B) Minus infinity
Description : Gibbs free energy at constant pressure and temperature under equilibrium conditions is (A) ∞ (B) 0 (C) Maximum (D) Minimum
Last Answer : (D) Minimum
Description : Gibbs free energy of mixing at constant pressure and temperature is always (A) 0 (B) ∞ (C) + ve (D) - ve
Last Answer : (D) - ve
Description : The standard Gibbs free energy change of a reaction depends on the equilibrium (A) Pressure (B) Temperature (C) Composition (D) All (A), (B) and (C)
Last Answer : (B) Temperature
Description : The pressure of the vapor phase of a substance that is in equilibrium with the liquid or solid phase. a. Phase Pressure b. Equilibrium Vapor Pressure c. Specific Pressure d. Equilibrium Phase Pressure
Last Answer : Equilibrium Vapor Pressure
Description : . A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because (A) Total heat transfer area of ... in a single effect is much lower than that in any effect in a multi-effect system
Last Answer : (B) Total amount of vapor produced per Kg of feed steam in a multiple effect system is much higher than in a single effect
Description : Occurs when the vapor pressure equals the atmospheric pressure a. Boiling b. Melting c. Freezing d. Vaporizing
Last Answer : Boiling
Description : The temperature at which the vapor pressure exactly equals one atm is called _________. a. boiling temperature b. normal boiling point c. triple point d. point of infliction
Last Answer : normal boiling point
Description : Which of the following properties is lower for a solution than for the pure solvent? w) osmotic pressure x) vapor pressure y) temperature z) boiling point
Last Answer : ANSWER: X -- VAPOR PRESSURE
Description : Which of the following properties is greater for a solution than for the pure solvent? w) freezing point x) vapor pressure y) temperature z) boiling point
Last Answer : ANSWER: D -- BOILING POINT
Description : __________ increases with increase in pressure. (A) The melting point of wax (B) The boiling point of a liquid (C) Both (A) and (B) (D) Neither (A) nor (B)
Last Answer : (C) Both (A) and (B)
Description : The change in Gibbs free energy for vaporisation of a pure substance is (A) Positive (B) Negative (C) Zero (D) May be positive or negative
Last Answer : (C) Zero
Description : In any spontaneous process, the __________ free energy decreases. (A) Helmholtz (B) Gibbs (C) Both ‘a’ & ‘b’ (D) Neither 'a' nor 'b'
Last Answer : (C) Both ‘a’ & ‘b’
Description : The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition. (A) Internal energy (B) Enthalpy (C) Gibbs free energy (D) Helmholtz free energy
Last Answer : (C) Gibbs free energy
Description : Gibbs free energy (G) is represented by, G = H - TS, whereas Helmholtz free energy, (A) is given by, A = E - TS. Which of the following is the Gibbs Helmholtz equation? (A) [∂(G/T)/∂T] = - (H/T2) (B) [∂(A/T)/∂T]V = - E/T2 (C) Both (A) and (B) (D) Neither (A) nor (B)
Description : Pick out the correct statement. (A) Like internal energy and enthalpy, the absolute value of standard entropy for elementary substances is zero (B) Melting of ice involves increase in enthalpy and ... of an ideal gas depends only on its pressure (D) Maximum work is done under reversible conditions
Last Answer : (D) Maximum work is done under reversible conditions
Description : Increase in the entropy of a system represents the (A) Degradation of energy (B) Decrease in system pressure (C) Increase in the availability of energy (D) Increase in the temperature
Last Answer : Option A
Description : If the solubilities of different components (in a liquid-liquid extraction system) increase with rise in temperature, then the temperature above which they dissolve completely is known as the critical solution ... On heating, a vapor phase will appear; while on cooling, a solid phase will appear
Last Answer : (D) On heating, a vapor phase will appear; while on cooling, a solid phase will appear
Description : Decoction refers to the use of solvent (A) At ambient temperature (B) At its boiling point (C) In its vapor form (D) None of these
Last Answer : (B) At its boiling point
Description : At normal boiling point, molar entropy of vaporisation is __________ Joule/K°.mole. (A) 72 (B) 92 (C) 142 (D) 192
Last Answer : (B) 92
Description : In the pressure cooker, cooking is faster because the increase in vapour pressure - (1) increase the specific heat (2) decreases the specific heat (3) decreases the boiling point (4) increases the boiling point
Last Answer : (4) increases the boiling point
Description : Absolute vapor pressure of petrofuels is found by Reid bomb which is heated in water bath to 100°F. In Reid apparatus, the ratio of the volume of air chamber to that of the liquid fuel chamber is (A) 4 (B) 3 (C) 2 (D) 1
Last Answer : (A) 4
Description : __________ is the temperature at which a gas-vapor mixture becomes saturated, when cooled at constant total pressure out of contact with a liquid. (A) Dew point (B) Bubble point (C) Dry bulb temperature (D) Wet bulb temperature
Last Answer : (A) Dew point
Description : If a two phase system is in physical equilibrium; then it means that, the (A) Escaping tendency of each component from the liquid phase to the vapor phase is exactly equal to that from vapor phase to liquid phase ... liquid phase is equal to that throughout the vapor phase (D) All (A), (B) and (C)
Description : Flooding in a vapor-liquid contacting equipment occurs in a tray, when the pressure drop through a tray is __________ the liquid head available in the downcomer. (A) Less than (B) More than (C) Same as (D) Very much less
Last Answer : (B) More than
Description : Bound moisture is that liquid which exerts an equilibrium vapor pressure __________ that of the pure liquid at the given temperature. (A) Less than (B) More than (C) Equal to (D) Either (A) or (B); depends on the solid
Last Answer : (A) Less than
Description : Relative volatility varies with the concentration of component for an ideal solution. The relative volatility of a binary mixture may be defined as the ratio of vapor pressure of component 'A' to that of ... law (D) Vapor phase obeys Dalton's law and liquid phase obeys Raoult's law
Last Answer : (D) Vapor phase obeys Dalton's law and liquid phase obeys Raoult's law
Description : Pick out the wrong statement. (A) The controlling resistance in case of heating of air by condensing steam is in the air film (B) The log mean temperature difference (LMTD) for ... a pure fluid at a given pressure from liquid to vapor or vice-versa occurs at saturation temperature
Last Answer : (C) In case of a 1 - 2 shell and tube heat exchanger, the LMTD correction factor value increases sharply, when a temperature cross occurs