Home
Class 11
CHEMISTRY
Predict the sign of DeltaG for the react...

Predict the sign of `DeltaG` for the reaction at a very low temperature for which `DeltaH is +ve` and `DeltaS` is positive.

Text Solution

AI Generated Solution

To determine the sign of ΔG for the reaction at a very low temperature where ΔH is positive and ΔS is also positive, we can use the Gibbs free energy equation: ### Step-by-Step Solution: 1. **Understand the Gibbs Free Energy Equation**: The Gibbs free energy change (ΔG) is given by the equation: \[ ΔG = ΔH - TΔS ...
Promotional Banner

Topper's Solved these Questions

  • THERMODYNAMICS

    CENGAGE CHEMISTRY ENGLISH|Exercise Paragraph for Problem|1 Videos

  • THERMODYNAMICS

    CENGAGE CHEMISTRY ENGLISH|Exercise Exercises (Linked Comprehension)|74 Videos

  • THERMODYNAMICS

    CENGAGE CHEMISTRY ENGLISH|Exercise Ex 6.5|30 Videos

  • STOICHIOMETRY

    CENGAGE CHEMISTRY ENGLISH|Exercise Archives Subjective|33 Videos

Similar Questions

Explore conceptually related problems

In which reaction Delta S is positive :-

What is the sign of DeltaS for a spontaneous reaction ?

Predict the sign of Delta G for a reaction that is exothermic and accompanied by an increase in entropy.

The signs of DeltaH,DeltaS and DeltaG for a non-spontaneous reaction at all temperature would e

For the reaction 2Cl(g) rarr Cl_(2)(g) , what are the signs of DeltaH and DeltaS ?

For an edothemic reaction, DeltaH is positive.

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. For the reaction at 298 K ,2A + B rarr C DeltaH =100 kcal and DeltaS=0.050 kcal K^(-1) . If DeltaH and DeltaS are assumed to be constant over the temperature range, above what temperature will the reaction become spontaneous?

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. A reaction has a value of DeltaH =-40 Kcal at 400 k cal mol^(-1) . The reaction is spontaneous, below this temperature , it is not . The values fo DeltaG and DeltaS at 400 k are respectively

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. For the reaction at 25^(@), X_(2)O_(4)(l) rarr 2XO_(2)(g) DeltaH=2.1 Kcal and DeltaS = 20 cal K^(-1) . The reaction would be

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. The enthalpy change for a certain rection at 300 K is -15.0 K cal mol^(-1) . The entropy change under these conditions is -7.2 cal K^(-1)mol^(-1) . The free energy change for the reaction and its spontaneous/ non-spontaneous character will be

CENGAGE CHEMISTRY ENGLISH-THERMODYNAMICS-Exercises (Subjective)
  1. The dissolution of ammonium chloride in water is an endothermic proces...

    Text Solution

    |

  2. Does an aqueous solution of Mg^(2+) ions have larger entropy before or...

    Text Solution

    |

  3. Predict the sign of DeltaG for the reaction at a very low temperature ...

    Text Solution

    |

  4. DeltaH and DeltaS are +ve. Under what conditions, process will be spon...

    Text Solution

    |

  5. What is the limitation of the first law of thermodynamics?

    Text Solution

    |

  6. Which of the following is an extensive property?

    Text Solution

    |

  7. Which one of the following is a state property/function?

    Text Solution

    |

  8. The heat of combustion of H(2)(g) at constant pressure and 300k is -28...

    Text Solution

    |

  9. The standard absolute entropy of a substance, (S^(Theta)) is the entro...

    Text Solution

    |

  10. If the enthalpy of combustion of diamond and graphite are -395.4 kJ mo...

    Text Solution

    |

  11. For a spontaneous process, which of the following is always true?

    Text Solution

    |

  12. H(2)(g) +(1)/(2)O(2)(g) rarr H(2)O(g) DeltaH =- 242 kJ mol^(-1) Bond...

    Text Solution

    |

  13. Which one of the following has the same value as Delta(f)H^(Theta), CO...

    Text Solution

    |

  14. For which of the following processes is DeltaS negative?

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

  17. What is the physical significance of free energy?

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |