Indian Institute of Technology Kharagpur
Department of Chemistry
Spring 2011-2012 Mid-semester Exam
Time: 2 Hrs
No. of Students: 700
Subject No: CY11001
Full Marks: 30
Subject Name: Chemistry (1st Year)
(a) Attempt ALL the questions.
(b) All parts of a question MUST be answered together.
(c) Numerical results MUST be reported in SI units.
(d) Explicitly mention the sign convention used.
(e) Clearly state whether you are using oxidation or reduction potentials in electrochemistry. (f) The question paper contains TWO pages.
[Supplied Data: R = 8.314 J mor1 ~ 1 ; 1 Faraday= 96,500 C mol-1]
Ql. (a) For air at temperatures near 25°C and pressure in the range of 0 bar to 50 bar, the JouleThomson coefficient (;J.JT) can be considered as 0.2 K bar- 1• Estimate the final temperature of air if 58 g of air at 25°C and 50 bar undergoes Joule-Thomson throttling to a final pressure of
(b) Calculate ~G for isothermal compression of 30.0 g of water from 1.0 bar to 100.0 bar at 25°C.
Consider Vis independent ofP in this range and density of water in this range is 0.997 g/cm3 .
(c) For Mercury, given that a (expansion coefficient)= I.82 x I 0-4 K- 1 and compressibility)= 3.87
w-s atm- 1 at 20 °C; find out (!lin SI unit.
(d) In the gas-phase reaction A+ 2B ~ 3C + 2 D, it was found that when 2.00 mol A, 1.00 mol B, and 3.00 molD were mixed and allowed to come to equilibrium at 25°C, the resulting mixture contained 0.79 mol Cat a total pressure of 1.00 bar. Calculate (i) Kx, (ii) Kpand (iii) ~Gr • The
symbols carry usual meaning. Assume the gases are ideal.
- ·- ---------- - - - -__ _ _ _ _ _!
Q2. (a) Standard reduction potentials (E') for the electrodes Au+ I Au, Au 3+I Au, and Fe3+1 Fe 2+ are
1.69 V, 1.40 V and 0. 77 V, respectively. Calculate the standard cell potential (E'ceu) and the equilibrium constant for the following reaction