What is the entropy change for the reaction given below, 

2H2 (g) + O2 (g) 2H2O(l)

at temperature 300 K? Standard entropies of H2 (g), O2(g) and H2O(l) are 126.6, 201.20 and 68.0 JK-1mol-1 respectively.

1. -318.4 JK-1mol-1                           .

2. 318.4 JK-1mol-1 

3. 31.84 JK-1mol-1                             

4. none of these

Subtopic:  Spontaneity & Entropy |
 72%
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If S° for H2, Cl2 and HCl are 0.13, 0.22 and 0.19 kJ K-1mol-1 respectively. The total change in standard entropy for the reaction, H2 + Cl2 2HCl is:

1. 30 J K-1mol-1                         

2. 40 J K-1mol-1

3. 60 J K-1mol-1                         

4. 20 J K-1mol-1

Subtopic:  Spontaneity & Entropy |
 80%
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The direct conversion of A to B is difficult and thus it is converted by path ACDB. Given

SAC=50 e.u; SCD=30 e.u; SBD=20 e.u.

(Where e.u. is the entropy unit)
then SAB would be:

1. +60 e.u                                       

2. +100 e.u

3. -60 e.u                                       

4. -100 e.u

Subtopic:  Hess's Law |
 61%
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In a flask, colourless N2O4(g) is in equilibrium with brown coloured NO2(g). At equilibrium when the flask is heated to 100°C, the brown colour deepens and on cooling it becomes less coloured. Which statement is incorrect about this observation?

1. The H for the reaction N2O4(g) 2NO2(g) is +ve

2. Paramagnetism increases on heating

3. The H-U at 100°C is equal to 200 cal

4. Dimerisation is reduced on heating

Subtopic:  First Law of Thermodynamics |
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Enthalpy of the reaction,

CH4(g) + 1/2O2(g) → CH3OH(l), is negative. If the enthalpy of combustion of CH4 and CH3OH are x and y respectively, then
which relation is correct?                                 

1. x>y         

2. x<y         

3. x=y           

4. xy

Subtopic:  Enthalpy & Internal energy |
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In the reaction, H and S both are positive. The condition under which the reaction would not be spontaneous is -

1. H>TS                             

2. S=H/T

3. H=TS                               

4. All of the above

Subtopic:  Gibbs Energy Change |
 54%
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When an ideal gas is compressed adiabatically and reversibly, the final temperature is:

1. higher than the initial temperature

2. lower than the initial temperature

3. the same as the initial temperature

4. dependent on the rate of compression

Subtopic:  First Law of Thermodynamics |
 57%
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1 liter-atmosphere is equal to:

1. 101.3 J                           

2. 24.20 cal

3. 101.3 x 107 erg               

4. All of the above

Subtopic:  First Law of Thermodynamics |
 69%
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The standard change is Gibbs energy for the reaction,

H2OH+ + OH- at 25°C is:

1. 100 kJ                         

2. -90 kJ

3. 90 kJ                           

4. -100 kJ

Subtopic:  Spontaneity & Entropy |
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The entropy change in the fusion of one mole of a solid melting at 27°C  is  -       

(the latent heat of fusion is 2930 J mol-1)                                                                                   

1. 9.77 JK-1mol-1               

2. 19.73 JK-1mol-1               

3. 2930 JK-1mol-1               

4. 108.5 JK-1mol-1          

Subtopic:  Spontaneity & Entropy |
 80%
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