Set No. 1

Code No: RR311804

1. (a) Explain the following terms with regard to diffusion in solids.

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i. Concentration gradient ii. Diffusion flux iii. Diffusivity.

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III B.Tech I Semester Supplimentary Examinations, November 2008 METALLURGICAL THERMO DYNAMICS (Metallurgy & Material Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆

(b) List the factors affecting diffusion. Discuss these factors in detail.

2. (a) Compare interstecial and vacancy atomic mechanisms for diffusion.

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(b) Cite 2 reasons why interstecial diffusion is normally more rapid than vacancy diffusion. [8]

3. (a) What is the importance of equilibrium constant & how this can be calculated from standard free energy changes? [8]

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(b) Define equilibrium constant & how this can be influenced on the extraction process. [8] 4. (a) Explain the differences between Einstein and Debye’s model of lattice specific heats. [8] (b) Consider a plate-glass window with a thickness of 0.5 cm and an area of 1000Cm2 . If the thermal conductivity for soda-lime glass is 1.7 W/m.k, estimate the heat loss through this window if the inside temperature is 25o C and the outside temperature is 0o C. [8]

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5. (a) Explain how the composition of a solution can be expressed.

[6]

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(b) One mole of solid Cr at 1873 K is added to a large quantity of liquid Fr-Cr solution at 1873 K with Xcr = 0.24. If Fe and Cr form ideal solution, Calculate the heat and entropy change in the system resulting from the addition. Ignore the difference of Cp between solid and liquid chromium. [10]

6. (a) How Gibbs Duhem (Integration) equation related with the ideal & non-ideal solutions? [8] (b) Derive the Gibbs Duhem equation & Integration of Gibbs Duhem equation. [8]

7. (a) What is the significance of phase rule? Discuss its applications and limitations. (b) Explain the differences between a liquidus line and solidus line. Explain how the liquidus line is obtained for an eutectic system. [8+8] 1 of 2

Set No. 1

Code No: RR311804

8. (a) Explain about the Galvanic cell & its sign convention & representation.

[8]

(b) What are the reversible and irreversible cells, Explain any one cell.

[8]

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Set No. 2

Code No: RR311804

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III B.Tech I Semester Supplimentary Examinations, November 2008 METALLURGICAL THERMO DYNAMICS (Metallurgy & Material Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆

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1. (a) Discuss the solution of Fick’s second law. In this light, Explain error function. What are the limitations of Fick’s laws. [8] (b) Describe the procedure for determining diffusivity by experimental technique. How do you account for the time and temperature effects. [8]

2. (a) Compare interstecial and vacancy atomic mechanisms for diffusion. [8] (b) Cite 2 reasons why interstecial diffusion is normally more rapid than vacancy diffusion. [8]

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3. (a) What is the importance of equilibrium constant & how this can be calculated from standard free energy changes? [8] (b) Define equilibrium constant & how this can be influenced on the extraction process. [8]

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4. (a) What are the differences between lattice thermal conductivity effects and thermo electric effects of solids. [8] (b) The volume of a cubical block of metal changes by 0.15%. When its temperature is raised by 30o C. Compute the coefficient of linear expansion of the metal. [8] 5. (a) Derive an expression for obtaining partial molal quantities from molal quantities. [8] (b) Define and Explain ideal and now ideal solutions write about Raoult’s law.[8]

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6. (a) What are the properties of solution that can be studied with the help of Gibbs Duhem equation? Explain them in detail. [8] (b) Write a short notes on Sievert’s law [8]

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7. (a) Explain the concept of chemical potential and derive the expressions related there in. Show that for any heterogeneous system of equillibrium, the chemical potential of each component has identical values in all the phases. (b) Disucss the graphical method of valuation of partial molal quantities from the molal quantity. [9+7]

8. (a) Explain about the electrochemical cells & its classification. [8] (b) How chemical / electrical energy can be calculated for any electrochemical cells. [8] ⋆⋆⋆⋆⋆ 1 of 1

Set No. 3

Code No: RR311804

1. (a) Explain the mechanisms of diffusion.

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III B.Tech I Semester Supplimentary Examinations, November 2008 METALLURGICAL THERMO DYNAMICS (Metallurgy & Material Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ [5]

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(c) Find the value of flux as given by Fick’s first law of diffusion.

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(b) Explain how does the diffusion constant vary with temperature?

2. (a) Compare interstecial and vacancy atomic mechanisms for diffusion.

[8]

(b) Cite 2 reasons why interstecial diffusion is normally more rapid than vacancy diffusion. [8]

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3. (a) Calculate the equilibrium constant for the reaction N iO + H2 = N i + H2 Oat750o C from the following data: Ni + 1/2 O2 = NiO ∆Go = −58, 450 + 2355T cal H2 + 1/2O2 = H2 O ∆Go = −58900 + 13.1T cal

[8]

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(b) Calculate the CO/CO2 ratio in equilibrium with Carbon at 727o C assuming that the total pressure to be 2 atm. 2C + O2 = 2CO ∆ Go 1000 = -95.3 kcal [8] C + O2 = CO2 ∆ Go 1000 = -94.0 kcal 4. (a) Explain WEIDEMANN - FRANZ ratio.

[6]

(b) For copper the heat capacity at constant volume Cv at 20k is 0.38 J/mol/K and the Debye temperature is 340k. Estimate the specific heat at [10]

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i. 40 K and ii. at 400 K.

(Assume any missing data).

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5. (a) Derive an expression for obtaining partial molal quantities from molal quantities. [8] (b) Define and Explain ideal and now ideal solutions write about Raoult’s law.[8]

6. (a) What are the properties of solution that can be studied with the help of Gibbs Duhem equation? Explain them in detail. [8] (b) Write a short notes on Sievert’s law

[8]

7. (a) Explain the concept of chemical potential and derive the expressions related there in. Show that for any heterogeneous system of equillibrium, the chemical potential of each component has identical values in all the phases. 1 of 2

Set No. 3

Code No: RR311804

(b) Disucss the graphical method of valuation of partial molal quantities from the molal quantity. [9+7] 8. Define the following:

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(a) Half cell potential

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(b) Decomposition potential (c) Standard electrode potential (d) Sign convention of electrode potentials (f) Electrical energy (g) Electrolysis (h) Cell representation

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(e) Nernst equation.

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Set No. 4

Code No: RR311804

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III B.Tech I Semester Supplimentary Examinations, November 2008 METALLURGICAL THERMO DYNAMICS (Metallurgy & Material Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Discuss the solution of Fick’s second law. In this light, Explain error function. What are the limitations of Fick’s laws. [8]

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(b) Describe the procedure for determining diffusivity by experimental technique. How do you account for the time and temperature effects. [8] 2. (a) Which mechanism of diffusion takes place in Nickle-FCC Iron system? How can you determine the number of effective jumps per unit item. [8] i. lattice diffusion ii. pipe diffusion.

[4+4]

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(b) Explain the following:

3. (a) What is the importance of equilibrium constant & how this can be calculated from standard free energy changes? [8]

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(b) Define equilibrium constant & how this can be influenced on the extraction process. [8] 4. (a) Discuss how the phenomenon of thermal expansion is explained in terms of the lattice vibrations in crystals. [8] (b) What are the different types of thermal conductivity in materials? How does each vary with temperature? [8] [6]

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5. (a) State and explain Sievert’s law.

(b) Define activity of a substance. Indicate the relationship between activity and mole fraction for an ideal solution. [10]

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6. (a) Explain the difference of crystal imperfect as on the stability of crystal disorders. [8] (b) What is the importance of Gibbs Duhem equation on Metallurgical processes? [8]

7. (a) Explain the concept of chemical potential and derive the expressions related there in. Show that for any heterogeneous system of equillibrium, the chemical potential of each component has identical values in all the phases. (b) Disucss the graphical method of valuation of partial molal quantities from the molal quantity. [9+7]

8. Define the following:

[2+8=16] 1 of 2

Set No. 4

Code No: RR311804 (a) Half cell potential (b) Decomposition potential (c) Standard electrode potential (d) Sign convention of electrode potentials (e) Nernst equation.

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(f) Electrical energy (g) Electrolysis

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(h) Cell representation

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