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Assertion (A): An exothermic process, no...

Assertion (A): An exothermic process, non-spontaneous at high temperature, may become spontaneous at low temperature.
Reason (R ) : With decrease in temperature, randomness (entropy) decreases.

A

If both (A) and (R ) are correct, and (R ) is the correct explanation for (A).

B

If the both (A) and (R ) are correct, but(R ) is not a correct explanation for (A).

C

If (A) is correct, but (R ) is incorrect.

D

If (A) is incorrect, but (R ) is correct.

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An endothermic process is non-spontaneous at some temperature . It can be spontaneous at………….temperature.

Assertion : An exothermic process which is non-spontaneous at high temperature may become spontaneous at low temperature. Reason : Spontaneous process is an irreversible process and may be reversed by some external agency.

Assertion (A): May endothermic reactions that are not spontaneous at room temperature become spontaneous at high temperature. Reason (R ) : Entropy of the system increases with increase in temperature.

In which case, process will be spontaneous at all temperature?

In which case, process will be spontaneous at all temperature?

Dependence of Spontaneity on Temperature: For a process to be spontaneous , at constant temperature and pressure , there must be decrease in free energy of the system in the direction of the process , i.e. DeltaG_(P.T) lt 0. DeltaG_(P.T) =0 implies the equilibrium condition and DeltaG_(P.T) gt 0 corresponds to non- spontaneity. Gibbs- Helmholtz equation relates the free energy change to the enthalpy and entropy changes of the process as : " "DeltaG_(P.T) = DeltaH-TDeltaS" ""..."(1) The magnitude of DeltaH does not change much with the change in temperature but the entropy factor TDeltaS change appreciably . Thus, spontaneity of a process depends very much on temperature. For endothermic process, both DeltaH and DeltaS are positive . The energy factor, the first factor of equation, opposes the spontaneity whereas entorpy factor favours it. At low temperature the favourable factor TDeltaS will be small and may be less than DeltaH, DeltaG will have positive value indicated the nonspontaneity of the process. On raising temperature , the factor TDeltaS Increases appreciably and when it exceeds DeltaH, DeltaG would become negative and the process would be spontaneous . For an expthermic process, both DeltaH and DeltaS would be negative . In this case the first factor of eq.1 favours the spontaneity whereas the second factor opposes it. At high temperature , when T DeltaS gt DeltaH, DeltaG will have positive value, showing thereby the non-spontaneity fo the process . However , on decreasing temperature , the factor , TDeltaS decreases rapidly and when TDeltaS lt DeltaH, DeltaG becomes negative and the process occurs spontaneously. Thus , an exothermic process may be spontaneous at low temperature and non-spontaneous at high temperature. When CaCO_(3) is heated to a high temperature , it undergoes decomposition into CaO and CO_(2) whereas it is quite stable at room temperature . The most likely explanation of it, is

Which of the following proces is (are) expected to be spontaneous at higher temperature but non-spontaneous at lower temperature?

With decrease in temperature, oxyhaemoglobin curve will become

With decrease in temperature, oxyhaemoglobin curve will become

A reaction is spontaneous at low temperature but non- spontaneous at high temperature. Which of the following is true for the reaction?

CENGAGE CHEMISTRY ENGLISH-THERMODYNAMICS-Exercises (Assertion-Reasoning)
  1. Assertion (A): The thermodynamic factor which determines the spontane...

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  2. Assertion (A): The Joules -Thomon coefficient for an ideal gas is zer...

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  3. Assertion (A): Enthalpy of graphite is lower than that of diamond. R...

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  4. Assertion: The enthalpy of formation of gaseous oxygen molecules at 29...

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  5. Assertion (A): Heat of neutralisation for both HNO(3) and HCI with NaO...

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  6. Assertion (A): Decrease in free energy causes spontaneous reaction ...

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  7. Many endothermic reactions that are not spontaneous at room temperatur...

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  8. Assertion (A): The enthalpy of formation of H(2)O(l) is greater than t...

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  9. Assertion (A): For a particular reaction, heat of combustion at consta...

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  10. Assertion (A): The enthalpy of both graphite and diamond is taken to ...

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  11. Assertion (A): The heat of neutralisation of perchloric acid, HCIO(4),...

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  12. Assertion (A): The Heat of ionisation of water is equal to the heat o...

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  13. Assertion (A): The enthalpy of formation of HCI is equal to the bond e...

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  14. Assertion (A): Pressure, volume, and temperature are all extensive pro...

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  15. Assertion (A): When a gas at high pressure expands against vacuum, th...

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  16. Assertion: When a real gas is allowed to expand adiabatically through ...

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  17. Assertion : There is no change in internal energ in a cyclic process. ...

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  18. Assertion (A): An exothermic process, non-spontaneous at high temperat...

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  19. Assertion (A): There is no reaction known for which DeltaG is positive...

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  20. A reaction which is spontaneous and accompanied by decrease of randomn...

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