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

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.

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.

For a process top be spontaneous, at constant temperature and pressure, there must be decreases in free energy of the system in the direction of the process, i.e. DeltaG_(P.T.)lt0.Delta_(P.T.)=0 implies the equilibrium condition and DeltaG_(P.T.)gt0 corresponding to non-spontaneity. Gibb's Helmholtz equation relates the free energy change to the enthalpy and entropy change of the process as : DeltaG_(P.T.)=DeltaH-TDeltaS ......(i) The magnitude of Delta H does not change much with the change in temperature but the entropy factor TDeltaS changes appreciably. Thus, spontaneity of a process depends very much on temperature. For edothermic proces, both DeltaH "and " DeltaS are positive. The energy factor,the first factor of equation, opposes the spontaneity whereas entropy factor favours it . At low temperature, the favourable factor TDeltaS will be small and may be less than Delta H, DeltaG will have positive value indicating the non-spontaneity 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 exothermic process, both DeltaH " and " DeltaS would be negative. In this case, the first factor of equation(i) favours the spontaneity whereas the second factor opposes it. At high temperature, when TDeltaSgt DeltaH, DeltaG will have positive value, showing thereby the non-spontaneity of the process. However, on decreasing temperature, the factore TDeltaSlt 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 reaction at 300K 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 :

For a process top be spontaneous, at constant temperature and pressure, there must be decreases in free energy of the system in the direction of the process, i.e. DeltaG_(P.T.)lt0.Delta_(P.T.)=0 implies the equilibrium condition and DeltaG_(P.T.)gt0 corresponding to non-spontaneity. Gibb's Helmholtz equation relates the free energy change to the enthalpy and entropy change of the process as : DeltaG_(P.T.)=DeltaH-TDeltaS ......(i) The magnitude of Delta H does not change much with the change in temperature but the entropy factor TDeltaS changes appreciably. Thus, spontaneity of a process depends very much on temperature. For edothermic proces, both DeltaH "and " DeltaS are positive. The energy factor,the first factor of equation, opposes the spontaneity whereas entropy factor favours it . At low temperature, the favourable factor TDeltaS will be small and may be less than Delta H, DeltaG will have positive value indicating the non-spontaneity 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 exothermic process, both DeltaH " and " DeltaS would be negative. In this case, the first factor of equation(i) favours the spontaneity whereas the second factor opposes it. At high temperature, when TDeltaSgt DeltaH, DeltaG will have positive value, showing thereby the non-spontaneity of the process. However, on decreasing temperature, the factore TDeltaSlt 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 298K, 2A+B toC" " Delta H =100 kcal and DeltaS= 0.050 kcal K^(-1) . If DeltaH " and " DeltaS are assumed to be constant over the temperature range, just above what temperature will be reaction become spontaneous?

For a process top be spontaneous, at constant temperature and pressure, there must be decreases in free energy of the system in the direction of the process, i.e. DeltaG_(P.T.)lt0.Delta_(P.T.)=0 implies the equilibrium condition and DeltaG_(P.T.)gt0 corresponding to non-spontaneity. Gibb's Helmholtz equation relates the free energy change to the enthalpy and entropy change of the process as : DeltaG_(P.T.)=DeltaH-TDeltaS ......(i) The magnitude of Delta H does not change much with the change in temperature but the entropy factor TDeltaS changes appreciably. Thus, spontaneity of a process depends very much on temperature. For edothermic proces, both DeltaH "and " DeltaS are positive. The energy factor,the first factor of equation, opposes the spontaneity whereas entropy factor favours it . At low temperature, the favourable factor TDeltaS will be small and may be less than Delta H, DeltaG will have positive value indicating the non-spontaneity 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 exothermic process, both DeltaH " and " DeltaS would be negative. In this case, the first factor of equation(i) favours the spontaneity whereas the second factor opposes it. At high temperature, when TDeltaSgt DeltaH, DeltaG will have positive value, showing thereby the non-spontaneity of the process. However, on decreasing temperature, the factore TDeltaSlt 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 400K . Above 400K, the reaction is spontaneous, below this temperature, it is not. The value of DeltaG " and "DeltaS at 400K are respectively:

For a process top be spontaneous, at constant temperature and pressure, there must be decreases in free energy of the system in the direction of the process, i.e. DeltaG_(P.T.)lt0.Delta_(P.T.)=0 implies the equilibrium condition and DeltaG_(P.T.)gt0 corresponding to non-spontaneity. Gibb's Helmholtz equation relates the free energy change to the enthalpy and entropy change of the process as : DeltaG_(P.T.)=DeltaH-TDeltaS ......(i) The magnitude of Delta H does not change much with the change in temperature but the entropy factor TDeltaS changes appreciably. Thus, spontaneity of a process depends very much on temperature. For edothermic proces, both DeltaH "and " DeltaS are positive. The energy factor,the first factor of equation, opposes the spontaneity whereas entropy factor favours it . At low temperature, the favourable factor TDeltaS will be small and may be less than Delta H, DeltaG will have positive value indicating the non-spontaneity 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 exothermic process, both DeltaH " and " DeltaS would be negative. In this case, the first factor of equation(i) favours the spontaneity whereas the second factor opposes it. At high temperature, when TDeltaSgt DeltaH, DeltaG will have positive value, showing thereby the non-spontaneity of the process. However, on decreasing temperature, the factore TDeltaSlt 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:

For a process top be spontaneous, at constant temperature and pressure, there must be decreases in free energy of the system in the direction of the process, i.e. DeltaG_(P.T.)lt0.Delta_(P.T.)=0 implies the equilibrium condition and DeltaG_(P.T.)gt0 corresponding to non-spontaneity. Gibb's Helmholtz equation relates the free energy change to the enthalpy and entropy change of the process as : DeltaG_(P.T.)=DeltaH-TDeltaS ......(i) The magnitude of Delta H does not change much with the change in temperature but the entropy factor TDeltaS changes appreciably. Thus, spontaneity of a process depends very much on temperature. For edothermic proces, both DeltaH "and " DeltaS are positive. The energy factor,the first factor of equation, opposes the spontaneity whereas entropy factor favours it . At low temperature, the favourable factor TDeltaS will be small and may be less than Delta H, DeltaG will have positive value indicating the non-spontaneity 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 exothermic process, both DeltaH " and " DeltaS would be negative. In this case, the first factor of equation(i) favours the spontaneity whereas the second factor opposes it. At high temperature, when TDeltaSgt DeltaH, DeltaG will have positive value, showing thereby the non-spontaneity of the process. However, on decreasing temperature, the factore TDeltaSlt 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 25^(@)C,X_(2)O_(2)(l) to 2XO_(2)(g)" "DeltaH=2.1 kcal and DeltaS=20 cal K^(-1) . The reaction would be:

Assertion: All endothermic reactions which are non-spontaneous at room temperature become spontaneous at high temperatures. Reason : Endothermic reactions become spontaneous if DeltaS is positive and TDeltaS gt DeltaH .

Statement-1 : Many endothermic reactions that are not spontaneous at room temperature become spontaneous at high temperatures. Statement-2: Energy of the system increases with increase in temperature.

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.