GTU BE 2019 Summer Question Papers || Gujarat Technological University
Subject Name: Chemical Engineering Thermodynamics - IT
Time: 02:30 PM TO 05:00 PM
Date: 31/05/2019
Total Marks: 70
Subject Code: 2150503
GUJARAT TECHNOLOGICAL UNIVERSITY
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BE - SEMESTER-V (NEW) EXAMINATION - SUMMER 2019Subject Name: Chemical Engineering Thermodynamics - IT
Time: 02:30 PM TO 05:00 PM
Date: 31/05/2019
Total Marks: 70
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Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
| Q.1 (a) | Discuss the phase rule and Duhem’s theorem. | 03 | ||||||||||||||||||||||||||||||
| (b) | Derive the expression of vapor composition at equilibrium using flash vaporization. | 04 | ||||||||||||||||||||||||||||||
| (c) | Derive the equation for criteria for phase equilibrium in terms of chemical potential for a mixture of N components and 7 phases. | 07 | ||||||||||||||||||||||||||||||
| Q.2 (a) | At 303 K the vapour pressures of benzene (1) and toluene (2) are 15.75 kPa and 4.89 kPa respectively. Determine the partial pressure and composition of the benzene vapour in equilibrium with a liquid mixture consisting of equal weight of the two components. | 03 | ||||||||||||||||||||||||||||||
| (b) | A 30 mol% methanol-water solution is to be prepared. How many cubic meters of pure methanol (molar volume 40.727 x 10-6 m3/mol) and pure water (molar volume 18.068 x 10-6 m3/mol) are to be mixed to prepare 2 m3 of the desired solution? The partial molar volumes of methanol and water in 30% solution are 38.632 x 10-6 m3/mol and 17.765 x 10-6 m3/mol respectively. | 04 | ||||||||||||||||||||||||||||||
| (c) | Define fugacity coefficient. Discuss any two methods to evaluate fugacity coefficient in details. | 07 | ||||||||||||||||||||||||||||||
| OR | ||||||||||||||||||||||||||||||||
| (c) | Water (1)/hydrazine (2) system forms ‘an azeotrope containing 58.5 mol% hydrazine at 393 K and 101.3 kPa. Calculate the equilibrium vapor composition for a solution containing 20 mol% hydrazine. The relative volatility of water with reference to hydrazine is 1.6 and may be assume to remain constant in the temperature range involved. Vapor pressure of hydrazine at 393 K is 124.76 kPa. | 07 | ||||||||||||||||||||||||||||||
| Q.3 (a) | Derive the Margules equations from the following expression: --- Content provided by FirstRanker.com --- GE / (x1x2RT) = A21 x1 + A12 x2 | 03 | ||||||||||||||||||||||||||||||
| (b) | Define partial molar properties and explain any one method in detail for evaluation of partial molar properties. | 04 | ||||||||||||||||||||||||||||||
| (c) | The following values refer to the Wilson parameters for the system of acetone (1)/water (2): a12 = 1225.31 J/mol, a21 = 6051.01 J/mol, V1 = 74.05 x 10-6 m3/mol and V2 = 18.07 x 10-6 m3/mol. The vapour pressures are given by the equations: ln Ps1 = 14.3915 - 2795.817 / (T - 43.198) and ln Ps2 = 16.262 - 3799.887 / (T - 46.854) where Ps is in kPa and T is in K. Calculate the equilibrium pressure and composition of vapour in equilibrium with a liquid of composition x1 = 0.43 at 349 K. | 07 | ||||||||||||||||||||||||||||||
| OR | ||||||||||||||||||||||||||||||||
| (b) | The experimental pressure-volume data for benzene at 675 K from a very low pressures up to 75 bar may be approximated by the equation V = 0.0554(1/P - 0.0046). Where V is in m3/mol and pressure P is in bar. What is the fugacity of benzene at 1 bar and 675 K? | 03 | ||||||||||||||||||||||||||||||
| (c) | What is gamma-phi formulation of VLE? Draw block diagrams for the BUBL P and DEW P calculations. Write all necessary equations. | 07 | ||||||||||||||||||||||||||||||
| Q.4 (a) | Write a short note on group contribution methods. | 03 | ||||||||||||||||||||||||||||||
| (b) | Define azeotrope and explain the minimum boiling and maximum boiling azeotropes with suitable examples. | 04 | ||||||||||||||||||||||||||||||
| (c) | Prove “Henry’s law applies to a species as it approaches infinite dilution in a binary solution, and the Gibbs/Duhem equation ensures the validity of the Lewis/Randall rule for the other species as it approaches purity. | 07 | ||||||||||||||||||||||||||||||
| OR | ||||||||||||||||||||||||||||||||
| Q.4 (a) | Explain the Lewis-Randall rule and its significance. | 03 | ||||||||||||||||||||||||||||||
| (b) | Write a brief note on retrograde condensation and its application. | 04 | ||||||||||||||||||||||||||||||
| (c) | Using fundamental properties relations establish the expression of standard Gibbs free energy change of chemical reaction as a function of thermodynamic equilibrium constant. | 07 | ||||||||||||||||||||||||||||||
| Q.5 (a) | Write down Raoult's Law and Henry's Law explaining each term associated with them with their applicability. | 03 | ||||||||||||||||||||||||||||||
| (b) | Explain T-x-y diagram for partial miscible system. | 04 | ||||||||||||||||||||||||||||||
| (c) | For an ideal gas, the exact mathematical expressions can be developed for the effect of T and P on the reaction co-ordinate at equilibrium. For conciseness we let H(T,P) = K. Then we can write the mathematical relations: (?H/?T)P = (?K/?T)P , (?H/?P)T = (?K/?P)T Using above equations, show that --- Content provided by FirstRanker.com --- (?K/?T)P = ?H / RT2 and (?K/?P)T = -?V / RT | 07 | ||||||||||||||||||||||||||||||
| OR | ||||||||||||||||||||||||||||||||
| Q.5 (a) | Write a brief note on solid - vapor equilibrium. | 03 | ||||||||||||||||||||||||||||||
| (b) | The ammonia synthesis reaction written as: 0.5 N2(g) + 1.5 H2(g) ? NH3(g) with 0.5 mol nitrogen and 1.5 mol hydrogen as the initial amounts of reactants and with the assumption that the equilibrium mixture is an ideal gas, show that: ee = 1 - (1 + 1.299 K P)0.5 | 04 | ||||||||||||||||||||||||||||||
| (c) | Estimate the equilibrium constant at 1000 K and 0.1 MPa for the reaction : CO2(g) + H2(g) ? CO(g) + H2O(g) taking into account the variation of ?Ho with temperature.
| 07 |
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