Heat of formation of SO2 is -298 kJ. What is the heat of combusti

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 Multiple Choice QuestionsMultiple Choice Questions

111.

Δ H and ΔS for a reaction are +30.558 kJ mol-1 and 0.066 kJ K-1mol-1 at 1 atm pressure. The temperature at which free energy change is equal to zero and the nature of the reaction below this temperature are :

  • 483 K, spontaneous

  • 443 K, non-spontaneous

  • 443 K, spontaneous

  • 463 K, non-spontaneous


112.

The enthalpy of vaporization of substance is 840 J mol-1 and its boiling point is -173°C. Its entropy of vaporization is :

  • 42 J mol-1 K-1

  • 21 J mol-1 K-1

  • 84 J mol-1 K-1

  • 8.4 J mol-1 K-1


113.

Given the following thermochemical equations:

Zn + 12O2 → ZnO + 84,000 cal

Hg + 12O2 → HgO + 21,700 cal

Accordingly the heat of reaction for the following reaction, Zn + HgO → Hg + heat is:

  • 105,700 cal

  • 61,000 cal

  • 62,300 cal

  • 60,000 cal


114.

The law of thermodynamics formulated by Dr.N. Nernst is :

  • first law of thermodynamics

  • second law of thermodynamics

  • third law of thermodynamics

  • both (a) and (b)


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115.

Heat of neutralization will be minimum for which of the following combination?

  • NaOH + H2SO4

  • NH4OH + CH3COOH

  • NaOH + HCl

  • NaOH + CH3COOH


116.

2 moles of helium gas expanded isothermally and irreversible at 27°C from volume 1 dm3 to 1 m3 at constant pressure of 100 kPa. Calculate the work done.

  • 99900 kJ

  • 99900 J

  • 34464.65 kJ

  • 34464.65 J


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117.

Heat of formation of SO2 is -298 kJ. What is the heat of combustion of 4 g of S ?

  • + 37 kJ

  • -37.15 kJ

  • + 298 kJ

  • 18.6 kJ


B.

-37.15 kJ

Heat of combustion is defined as the change in total heat accompanying when one mole of substance undergoes complete combustion in excess of oxygen.

S + O2 → SO2H = 298 kJ

 Heat of formation of SO2 = heat of combustion of SO2

Atomic mass of S = 32 gm

 Combustion of 4 gm of S gives heat

-29832 × 4 

= -37.25 kJ


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118.

For the reaction

PCl5(g) → PCl3(g) + Cl2(g)

  • ΔH = ΔE

  • ΔH > ΔE

  • ΔH < ΔE

  • None of these


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119.

Which of the following is not a state function?

  • Internal energy

  • Enthalpy

  • Work

  • Entropy


120.

Enthalpy (H) is equal to

  • internal energy (E)

  • product of pressure (p) and volume (V) of gas

  • internal energy (E)+ pV

  • work (W) done by a system


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