An ideal gas expands in volume from \(1×10^{–3} m^3\) to \(1×10^{–2} m^3\) at 300 K against a constant pressure of 1×105 Nm-2. The work done is:

1. –900 J 2. –900 kJ
3. 270 kJ 4. 900 kJ

Subtopic:  First Law of Thermodynamics |
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The enthalpies of combustion of carbon and carbon monoxide are -393.5 and -283 kJ mol-1 respectively. The enthalpy of the formation of carbon monoxide per mole is:

1. 110.5 kJ

2. 676.5 kJ

3. -676.5 kJ

4. -110.5 kJ

Subtopic:  Hess's Law | Thermochemistry |
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The enthalpy changes for the following processes are listed below : 

Cl2 (g) → 2Cl(g), 242.3 kJ mol-1 

I2 (g) → 2I (g), 151.0 kJ mol-1 

ICI (g) → I(g) + Cl(g), 211.3 kJ mol-1 

I2 (s) → I2 (g), 62.76 kJ mol-1

Given that the standard states for iodine and chlorine  are I2 (s) and Cl2 (g), the standard enthalpy of formation of ICI (g) is : 

1. -14.6 kJ mol-1 

2. -20.8 kJ mol-1 

3. +16.8  kJ mol-1 

4. +244.8  kJ mol-1

Subtopic:  Hess's Law |
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\((\Delta H-\Delta U)\)  for the formation of carbon monoxide (CO) from its elements at 298 K is : 

(R = 8.314 JK-1 mol-1)

1. -1238.78 J mol-1 

2. 1238.78 J mol-1 

3. -2477.57 J mol-1 

4. 2477.57 J mol-1

Subtopic:  Enthalpy & Internal energy |
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If a reaction is non-spontaneous at the freezing point of water but is spontaneous at the boiling point of water, then:

\(\Delta H\) \(\Delta S\)
1.  +ve  +ve 
2.  -ve -ve
3. -ve  +ve 
4.  +ve  -ve

Subtopic:  Spontaneity & Entropy |
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If at 298 K the bond energies of C-H, C-C, C = C and H-H bonds are respectively 414, 347, 615, and 435 kJ mol–1, the value of enthalpy change for the reaction at 298 K will be:

\(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}(g)+\mathrm{H}_{2}(g) \longrightarrow \mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}(g)\)

1. +250 kJ 

2. –250 kJ 

3. +125 kJ 

4. –125 kJ 

Subtopic:  Thermochemistry |
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The internal energy change when a system goes from state A to B is 40 k J/mol . If the system goes from A to B by a reversible path and returns to state A by an irreversible path, what would be the net change in internal energy? 

1. 40 kJ 

2. > 40kJ 

3. < 40 kJ 

4. zero

Subtopic:  Enthalpy & Internal energy |
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Assuming that water vapor is an ideal gas, the internal energy change (∆U) when 1 mol of water is vaporized at 1 bar pressure and 100°C, will be:

(Given: Molar enthalpy of vaporization of water at 1 bar and 373 K = 41 kJ mol–1 and R = 8.3 J mol–1 K–1

1. 4.100 kJ mol–1

2. 3.7904 kJ mol–1

3. 37.904 kJ mol–1

4. 41.00 kJ mol–1

Subtopic:  Enthalpy & Internal energy |
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Standard entropy of X2, Y2 and XY3 are 60, 40 and 50 JK-1mol-1, respectively. For the reaction, 12X2+ 32Y2XY3H=-30kJ, to be at equilibrium, the temperature will be

1. 500 K

2. 750 K

3. 1000 K

4. 1250 K

Subtopic:  Spontaneity & Entropy |
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The oxidizing power of chlorine in an aqueous solution can be determined by the following parameters:
\(\small{\frac{1}{2} \left(Cl\right)_{2} \left(g\right) \overset{\frac{1}{2} \left(\Delta\right)_{diss} H^{\Theta}}{\rightarrow} Cl \left(g\right) \overset{\left(\Delta\right)_{eg} H^{\Theta}}{\rightarrow} \left(Cl\right)^{-} \left(g\right) \overset{\left(\Delta\right)_{hyd} H^{\Theta}}{\rightarrow} \left(Cl\right)^{-} \left(aq\right)}\)
The energy involved in the conversion of \({ 1 \over 2}Cl_2(g)\) to \(Cl^-\)(aq) will be:
Use the following data:
\(\Delta_{\text {diss }} H^{\circ}\left(\mathrm{Cl}_2\right)=240 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
\(\Delta_{\mathrm{eg}} H^{\circ}(\mathrm{Cl})=-349 \mathrm{~kJ} \mathrm{~mol}^{-1}\) \(\Delta_{\mathrm{hyd}} H^{\circ}\left(\mathrm{Cl}^{-}\right)=-381 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
1. - 610 kJ mol-1 2. - 850 kJ mol-1
3. +120 kJ mol-1 4. +152   kJ mol-1
Subtopic:  Hess's Law |
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