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What is significance of T DeltaS in Delt...

What is significance of `T DeltaS` in `DeltaG = DeltaH - T DeltaS`?

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It is quantitative measure of the randomness of the system.
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Significance Of Delta

Correct relation for isothermal reversible expansion of an ideal gas is DeltaS = 0 DeltaG = - T DeltaS DeltaH != 0 DeltaU != 0

Work done by the system in isothermal reversible process is w_(rev.)= -2.303 nRT "log"(V_(2))/(V_(1)) . Also in case of adiabatic reversible process work done by the system is given by: w_(rev.) = (nR)/(gamma -1) [T_2 - T_1] . During expansion disorder increases and the increase in disorder is expressed in terms of change in entropy DeltaS = q_(rev.)/T . The entropy changes also occurs during transformation of one state to other end expressed as DeltaS = DeltaH/T . Both entropy and enthalpy changes obtained for a process were taken as a measure of spontaniety of process but finally it was recommended that decrease in free energy is responsible for spontaniety and DeltaG=DeltaH - T DeltaS . The heat of vaporisation and heat of fusion of H_2O are 540 cal//g and 80 cal//g . This ratio of (DeltaS_(vap.))/(DeltaS_("fusion")) for water is:

Gibbs-Helmoholtz equation relates the free energy change to the enthalpy and entropy changes of the process as (DeltaG)_(PT) = DeltaH - T DeltaS The magnitude of DeltaH does not change much with the change in temperature but the enrgy factor T DeltaS changes appreciably. Thus, spontaneity of a process depends very much on temperature. For the reaction at 298K, 2A +B rarr C Deltah = 100 kcal and DeltaS = 0.020 kcla K^(-1) . If DeltaH and DeltaS are assumed to be constant over the temperature range, at what temperature will the reaction become spontaneous?

Free enegry , G = H - TS , is state function that indicates whther a reaction is spontaneous or non-spontaneous. If you think of TS as the part of the system's enegry that is disordered already, then (H -TS) is the part of the system's energy that is still ordered and therefore free to cause spontaneous change by becoming disordered. Also, DeltaG = DeltaH - T DeltaS From the second law of thermodynamics, a reaction is spontaneous if Delta_("total")S is positive, non-spontaneous if Delta_("total")S is negative, and at equilibrium if Delta_('total")S is zero. Since, -T DeltaS = DeltaG and since DeltaG and DeltaS have opposite sings, we can restate the thermodynamic criterion for the spontaneity of a reaction carried out a constant temperature and pressure. IF DeltaG lt 0 , the reaction is spontaneous. If DeltaG gt 0 , the reaction is non-spontaneous. If DeltaG = 0 , the reaction is at equilibrium. Read the above paragraph carefully and answer the following questions based on the above comprehension. For the spontaneity of a reaction, which statement is true?

CENGAGE CHEMISTRY-THERMODYNAMICS-Exercises (Subjective)
  1. For which of the following processes is DeltaS negative?

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  2. Predict DeltaH gt DeltaU or DeltaH lt DeltaU. a. C("graphite") +O(2)...

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  3. What is significance of T DeltaS in DeltaG = DeltaH - T DeltaS?

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  4. What is the physical significance of free enegry?

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  5. How does T DeltaS determine the spontaneity of process?

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  6. N(2)(g) +3H(2)(g) rarr 2NH(3): DeltaH =- 92 kJ is Haber's process for...

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  7. The energy released in the neutralisation of H(2)SO(4) and KOH is 59.1...

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  8. CH(4)(g) +2O(2)(g) rarr CO(2)(g) +2H(2)O(l), DeltaH =- 890 kJ what i...

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  9. H(2)(g) +CI(2)(g) rarr 2HCI(g) +185 kJ. State whether this reaction is...

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  10. The heat of neutralization of a strong acid by a strong base is a cons...

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  11. Explain why heat of neutralisation of strong acid and weak base is les...

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  12. Find the enthalpy of formation of hydrogen flouride on the basis of fo...

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  13. Calculate DeltaH for the reaction H(2)(g)+1//2O(2)(g)toH(2)O(g) gi...

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  14. Calculate the resonance enegry of NO(2) ( :O-N=O: ) The measured ent...

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  15. Boiling point of an organic compound is 310K. Its enthalpy of vaporisa...

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  16. Predict whether the following reaction is possible or not at 300k. 2...

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  17. Calculate the standard free energy change for the reaction: H(2)(g)...

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  18. Calculate the entropy change for the following reaction H(2)(g) +CI(...

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  19. Heat of neutralisation between HCI and NaOH is 13.7kcal and between HC...

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  20. Find the heat of formation of ethyl alcohol for following data C(s) ...

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