JNTU
JNTU B.Tech II MATERIALS THERMODYNAMICS Previous Question Paper (October - 2020 - R18)
Answer any five questions. All questions carry equal marks.
Main
Determine the relationship between pressure and the volume of an ideal gas undergoing a reversible adiabatic process.
Answer
For a reversible adiabatic process, the heat exchange is zero (dQ = 0). According to the first law of thermodynamics, dU = -dW, which implies CvdT = -PdV. Using the ideal gas law PV = nRT, we differentiate to get PdV + VdP = nRdT. Substituting dT = (PdV + VdP) / nR into the energy equation, we obtain Cv(PdV + VdP) / nR = -PdV. Since R = Cp - Cv and the ratio of specific heats is γ = Cp / Cv, this simplifies to dP/P + γ(dV/V) = 0. Integrating this expression yields ln P + γ ln V = constant, which results in the relationship PVγ = constant.
Define Specific heat and show that
Answer
Specific heat is defined as the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius or Kelvin. For an ideal gas, the molar heat capacity at constant pressure is Cp = (dH/dT)P and at constant volume is Cv = (dU/dT)V.
Starting from the enthalpy definition H = U + PV, and for one mole of an ideal gas where PV = RT, we have H = U + RT. Differentiating with respect to temperature T gives:
Substituting the definitions of specific heats:
Rearranging the terms yields the final relationship:
What is “system”? Classify different types of systems and give suitable examples.
Answer
Sign in to view the complete answer paper.
What is equilibrium? Categorize different types of equilibrium?
Answer
Sign in to view the complete answer paper.
Discuss concept of entropy and 3rd law of thermodynamics.
Answer
Sign in to view the complete answer paper.
Calculate the standard entropy of solid copper at 1073°C from the following data:
S°300 <Cu> = 8.0 Cal/deg/mole
Answer
Sign in to view the complete answer paper.
Define thermal efficiency? Explain the determinations of thermal efficiency of a heat engine.
Answer
Sign in to view the complete answer paper.
Zinc melts at 420°C and its standard entropy at 25°C is 9.95 cal/deg/mole. Calculate the standard entropy of Zinc at 750°C.
Given:
Answer
Sign in to view the complete answer paper.
Explain Duhringes rule for the estimation of the vapour pressure of an element with suitable examples.
Answer
Sign in to view the complete answer paper.
Analyze the concept of free energy. Classify the various types of free energy terms? Give their importance.
Answer
Sign in to view the complete answer paper.
Explain various forms of the Clausius-Clapeyron equation.
Answer
Sign in to view the complete answer paper.
Calculate Equilibrium constant and equilibrium partial pressure of oxygen at 1727°C for the reaction,
Answer
Sign in to view the complete answer paper.
Compare Raoult’s law and Sievert’s law? Give their usefulness.
Answer
Sign in to view the complete answer paper.
Derive Gibbs’ Duhem equation in terms of partial molar quantities.
Answer
Sign in to view the complete answer paper.
State and explain Ellingham diagram for various metal oxides.
Answer
Sign in to view the complete answer paper.
Discuss about importance of Ellingham diagram in metallurgy and discuss its important characteristics.
Answer
Sign in to view the complete answer paper.