The gas absorbs 100 J heat and is simultaneously compressed by a constant external pressure of 1.50 atm from 8 lit. to 2 lit. in volume. Hence E will be-

1. -812 J

2. 812 J

3. 1011 J

4. 911 J

Subtopic:  Enthalpy & Internal energy |
 55%
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The standard heat of combustion of Al is -837.8 kJ mol-1 at 25C which of the following releases 250 kcal of heat ?

1. The reaction of 0.624 mol of Al

2. The formation of 0.624 mol of Al2O3

3. The reaction of 0.312 mol of Al

4. The formation of 0.150 mol of Al2O3

Subtopic:  Thermochemistry |
 65%
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Following reaction occurs at 25C :

2NOg, 1×10-5 atm+Cl2g, 1×10-2 atm2NOClg, 1×10-2 atmG is :

1. -45.65 kJ

2. -28.53 kJ

3. -22.82 kJ

4. -57.06 kJ

Subtopic:  Gibbs Energy Change |
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The bond energies ofCC, C-H, H-H and C=C are 198, 98, 103 and145 kcal respectively. The enthalpy change of the reaction HCCH+H2C2H4 is:

1. 48 kcal

2. 96 kcal

3. -40 kcal

4. -152 kcal

Subtopic:  Enthalpy & Internal energy |
 76%
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The enthalpies of formation of CO2(g) and CO(g) at 298 K are in the ratio 2.56 : 1. For the reaction,

CO2(g)+C(s)2CO(g), H=177.5kJ,
Hf of CO(g)  is-

1. -150.6 kJ mol-1

2. -113.78 kJ mol-1

3. -130.2 kJ mol-1

4. -141.8 kJ mol-1

Subtopic:  Enthalpy & Internal energy |
 61%
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The enthalpies of the following reactions are shown alongwith.

12H2g+12O2gOHg ; H=42.09 kJ mol-1
H2g2Hg;                      H=435.89 kJ mol-1
O2g2Og;                      H=495.05 kJ mol-1

Calculate the O-H bond energies for the hydroxyl radical.

1. 223.18 kJ mol-1

2. 423.38 kJ mol-1

3. 513.28 kJ mol-1

4. 113.38 kJ mol-1

Subtopic:  Thermochemistry |
 76%
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4.8 g of C(diamond) on complete combustion evolves 1584 kJ of heat. The standard heat of formation gaseous carbon is 725 kJ/mol. The energy required for the process

(i) C(graphite)C(gas)

(ii) C(diamond)C(gas)are

1. 725, 727

2. 727, 725

3. 725, 723

4. None of these

Subtopic:  Hess's Law |
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The reaction 3O2(g)2O3(g) is endothermic. What can be concluded about the average energy per bond in O2 and O3?

1. The average energy per bond in O2 is greater than that in O3

2. The average energy per bond in O2 is less than that in O3

3. The average energy per bond in O2 is equal to that is O3

4. Number conclusion can be drawn about the average bond energies from this information done

Subtopic:  Enthalpy & Internal energy |
 60%
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The amount of heat required to raise the temperature of 1 mole diatomic gas by 1°C at constant pressure is 60 cal. The amount of heat which goes as internal energy of the gas is nearly

1. 60 cal

2. 30 cal

3. 42.6 cal

4. 49.8 cal

Subtopic:  Cp & Cv |
 53%
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An ideal gas is taken through the cycle ABC as shown in figure, if net heat supplied to the gas in the cycle is 5 J, the work done by the gas in the process CA is

1. -5 J

2. -10 J

3. -15 J

4. -20 J

Subtopic:  2nd & 3rd Law of Thermodynamics |
 59%
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