Change in entropy is negative for:

1. Bromine (l)Bromine(g)

2. C(s) + H2O(g) CO(g) + H2(g)

3. N2(g,10 atm)N2(g,1 atm) 

4. Fe ( 1mol, 400 K)  Fe( 1mol, 300 K)

Subtopic:  Spontaneity & Entropy |
 70%
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For the following given equations and H° values, determine the enthalpy of reaction at 298 K for the reaction-

C2H4(g) + 6F2(g)  2CF4(g) + 4HF(g)

H2(g) + F2(g)  2HF(g)       H1°= -537 kJ

C(s) + 2F2(g) CF4(g)         H2°=-680 kJ

2C(s) + 2H2(g) C2H4(g)    H3°= 52 kJ

1. -1165 

2. -2486

3. +1165

4. +2486

Subtopic:  Enthalpy & Internal energy |
 82%
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Entropy decreases during:

1. Crystallization of sucrose from solution

2. Rusting of iron

3. Melting of ice

4. Vaporization of camphor

Subtopic:  Spontaneity & Entropy |
 82%
From NCERT
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A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of 37.0ºC. As it does so, it absorbs 208 J of heat. The values of q and w for the process will be-
(R = 8.314 J/mol K) (ln 7.5 = 2.01)

1. q = +208 J, w = -208 J 2. q = -208 J, w = -208 J
3. q = -208 J, w = + 208 J 4. q = +208 J, w = + 208 J
Subtopic:  First Law of Thermodynamics |
 78%
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Hf0 (298K) of methanol is given by the chemical equation -

1. C(diamond)+12O2+2H2CH3OH

2. CH4+12O2CH3OH

3. CO+2H2CH3OH

4. C(graphite)+12O2+2H2CH3OH

Subtopic:  Thermochemistry |
 75%
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When 4 g of iron is burnt to ferric oxide at a constant pressure, 29.28 kJ of heat is evolved.

The enthalpy of formation of ferric oxide will be-

(At. mass of Fe = 56) ?

1. -81.98 kJ

2. - 819.8 kJ

3. - 40.99 kJ

4.  +819.8 kJ

Subtopic:  Thermochemistry |
 60%
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The entropy change in the isothermal reversible expansion of 2 moles of an ideal gas from 10 to 100 L at 300 K is

1. 42.3 J K-1

2. 35.8 J K-1

3. 38.3 J K-1

4. 32.3 J K-1

Subtopic:  Spontaneity & Entropy |
 70%
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As an isolated box, equally partitioned, contains two ideal gasses A and B as shown:

 

When the partition is removed, the gases mix. The changes in enthalpy (H) and entropy (S) in the process, respectively, are

1. Zero, positive

2. Zero, negative

3. Positive, zero

4. Negative, zero

Subtopic:  Enthalpy & Internal energy |
 77%
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Hydrolysis of sucrose is given by the following reaction

Sucrose + H2 Glucose + Fructose

If the equilibrium constant (Kc) is 2×1013 at 300 K, the value of rG at the same temperature will be:

1. 8.314 J mol–1 K–1×300 K×ln (2×1013)

2. 8.314 J mol–1 K–1×300 K×ln (3×1013)

3. –8.314 J mol–1 K–1×300 K×ln (4×1013)

4. –8.314 J mol–1 K–1×300 K×ln (2×1013)

Subtopic:  Gibbs Energy Change |
 78%
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NEET - 2020
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The enthalpies of formation of Al2O3 and Cr2O3 are – 1596 kJ and – 1134 kJ, respectively. ∆H for the reaction 2Al + Cr2O3 → 2Cr + Al2O3 is -

1. –1365 kJ 2. 2730 kJ
3. –2730 kJ 4. –462 kJ
Subtopic:  Hess's Law |
 76%
From NCERT
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