Saturday 21 February 2015

CHEMICAL ENGINEERING – 2003 ,PAPER –II, SECTION A

                    Time Allowed: Three Hours                 Maximum Marks: 200
Candidates should attempt Questions 1 and 5 which are compulsory, and any THREE of the remaining questions selecting at least ONE question from each Section. Assume suitable data, if considered necessary, and indicate the same clearly.

SECTION A

1.       Answer any four of the following:

(a)    The normal boiling point of benzene (C₆H₆) is 80.1 °C and its latent heat of vaporization at 45°C.

(b)   Prove that two reversible, adiabatic lines cannot intersect.

(c)    Prove that
                             (əC / əv)  ̞ = T (ə²P / ə T²) ᵥ  

(d)   For an ideal batch reactor , derive and expression to determine the time required to achieve a desired conversion 

(e)   Compare the size of plug flow and mixed flow reactors, for first and second order reactions.

2.       Ethane (C₂H₆) is initially mixed with oxygen to obtain a mixture of 80% ethane by volume. This mixture is burned in an engine with 200% excess air. During combustion 80% of ethane burns to CO₂; 10% of ethane burns to CO and 10 % of ethane remains unburned. Determine the composition of the exhaust gas on dry basis.

3.       (a) For a particulate binary system the activity coefficients are adequately represented by in γ₁ = 0.5 X ²₂ and in γ₂ = 0.5 X ²₁ the saturated pressures of the components at 80°C are P ₁̾ = 600 torr (1 torr =1 mm Hg column). Is it possible for the system to exhibit azeotropy at 80°C? If so, what is the azeotropic composition?

                  (b) Show that for a van der Waals gas C ᵥ is a function of temperature only.

4.        Consider the reaction
                                                      {R (Desired Product)}
                        A + B =   -----       { S (Unwanted Product) }
           With the rate equations
               dCᵣ / dt = 1.0 C ¹  ͘⁵ C b ⁰  ̇³      mol / liter min
              dC s / dt   = 1.0 Ca ⁰  ̇ ⁵  Cb ¹  ̇ ⁸     mol / liter min
              Equal volumetric flow rates of A and B streams are fed to the reactor and each stram has a concentration of 20 mol/ liter of reactant. For 90% conversion of A, calculate the concentration of R in the product stream for---

           (a)    A plug flow reactor ;
           (b)   A mixed flow reactor.

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