Thermodynamics

Which of the following statements concerning the second and third laws of thermodynamics is/are true? (I) When the change in entropy of the system is equal in magnitude and opposite in sign to the change in entropy of the surroundings, the change in entropy of the universe is zero. (II) The change in entropy of the universe can be rewritten as −∆Gsytem/T. (III) In a perfect, pure crystal at absolute zero the entropy of the system is zero. 

1. III only 

2. II, III 

3. I only 

4. I, III

5. II only 

6. I, II, III 

7. I, II

Graph below show the entropy versus energy U of two system 1 and 2 at constant volume. The initial energies of the systems are indicated by U₁, i and U₂, i,

If I have 1 L ammonia at room pressure and temperature (100 kPa, 20°C) how much mass is that?  

Which of the following state functions are extensive? (I) Pressure (P) (II) Temperature (T) (III) Enthalpy (H) 

1. II only 

2. II, III 

3. I, III 

4. I, II, III 

5. I only 

6. III only 

7. I, II 

8. None are true

Steam at gauge pressure of 1.5Mpa is supplied to a steam turbine, which rejects it to a condenser at a vacuum of 710mm Hg after expansion. Find the inlet and exhaust steam pressure in pascal, assuming barometer pressure as 76cm of Hg and density of Hg as 13.6×10³ kg/m^3.

 The pressure of a gas in a pipeline is measured with a mercury manometer having one limb open. The difference in the level of the two limbs is 562mm. Calculate the gas pressure in terms of bar.

Determine the mass of an ethane gas stored in a 25 ft³ tank at 250 F, 440 lbf/in.² using the compressibility chart. Estimate the error (%) if the ideal gas model is used. 

Why do we write ΔE or E₂ – E₁ whereas we write ₁Q₂ and ₁W₂?

Consider a hot-air heating system for a home. Examine the following systems for heat transfer. 

(a) The combustion chamber and combustion gas side of the heat transfer area. 

(b) The furnace as a whole, including the hot- and cold-air ducts and chimney. 

Determine the size of a spherical balloon filled with hydrogen at 30°C and atmospheric pressure for lifting 400Kg payload. Atmospheric air is at temperature of 27°C and barometer reading is 75cm of mercury.