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Answer the following in one or two sentences. Comment on spontaneity of reactions for which ∆H is positive and ∆S is negative.

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प्रश्न

Answer the following in one or two sentences.

Comment on the spontaneity of reactions for which ∆H is positive and ∆S is negative.

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उत्तर

When ∆H positive and ∆S is negative, then ∆G is positive regardless of temperature. Such reactions are nonspontaneous at all temperatures.

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पाठ 4: Chemical Thermodynamics - Exercises [पृष्ठ ८७]

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बालभारती Chemistry [English] Standard 12 Maharashtra State Board
पाठ 4 Chemical Thermodynamics
Exercises | Q 2.8 | पृष्ठ ८७

संबंधित प्रश्‍न

Define entropy.


Answer in brief.

What is entropy? Give its units.


Answer the following question.

Although ΔS for the formation of two moles of water from H2 and O2 is –327J K–1, it is spontaneous. Explain.
(Given ΔH for the reaction is –572 kJ).


Answer the following question.

Obtain the relation between ΔG and `triangle "S"_"total"`. Comment on the spontaneity of the reaction.


Equilibrium constant for a reaction is 20. What is the value of ΔG° at 300 K? (R = 8 x 10-3 kJ)


One mole of NaCl(s) on melting absorbed 30.5 kJ of heat and its entropy increased by 28.8 J K−1. The melting point of NaCl is ____________.


For a process, entropy change of a system is expressed as ________.


In how many of the following, ∆S is positive?

i. Melting of ice

ii. Sublimation of iodine

iii. Dissolution of CuSO4 in water

iv. Condensation of water vapour

v. Dissociation of H2 molecule into atoms

vi. Conversion of carbon dioxide gas to dry ice

vii. Vaporization of acetone


In which of the following, ∆S is positive?


Which one of the following has ΔS0 greater than zero?


For the following reaction:

\[\ce{Fe2O3_{(s)} + 3CO_{(g)} -> 2Fe_{(s)} + 3CO2_{(g)}}\]; ΔH0 = −29.8 kJ and ΔS0 = 15 J K−1. What is the value of \[\ce{ΔS_{(total)}}\] at 298 K?


Equilibrium constant for a reaction is 20. What is the value of ∆G0 at 300 K? (R = 8 × 10−3 kJ)


Which of following is residual entropy of a substance?


Standard molar entropy is ______.


Calculate the amount of heat liberated during formation of 2. 7 kg of water if heat of formation of water is - 284.5 kJ mol-1.


The equilibrium constant for a reaction is 10, value of ΔG° at 300 K is (R = 8 × 10-3 kJ)


Relation between ΔH and ΔU for the reaction, \[\ce{2SO_{3(g)} -> 2SO_{2(g)} + O_{2(g)}}\] is _______.


Standard enthalpy and standard entropy changes for the oxidation of ammonia at 298 K are −382.64 kJ mol−1 and −145.6 JK−1 mol−1, respectively. Standard Gibb's energy change for the same reaction at 298 K is ______.


Dinitrogen and dioxygen combined to form nitrous oxide in equilibrium at 850 K. The equilibrium constant for this reaction is 0.56. If the equilibrium concentration of nitrous oxide gas is 3 × 10-3 M and both dinitrogen and dioxygen have the same concentration, then what will be the concentration of dinitrogen gas in M?


Identify whether the following pair have a larger entropy or not. If yes then Why?

O2{g) at 1 atm or O2(g) at 10 atm both at the same temperature.


What is a spontaneous process? What are its characteristics?


For a certain reaction ΔH0 is −224 kJ and ΔS0 is −153 J K−1. At what temperature the change over from spontaneous to non-spontaneous will occur?


Calculate ΔG0 for the reaction

\[\ce{CH_{4(g)} + H_{2(g)}-> C2H_{6(g)}}\]

State whether the reaction is spontaneous or not. (Given: KP = 3.358 × 1017, T = 25° C, R = 8.314 × 10−3 kJK−1 moI−1)


Define second law of thermodynamics.


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