Question

An endothermic reaction proceeds in the forward direction with decrease of temperature.
A. True
B. False

Answer 1

Hint: An endothermic process is any process with an increase in the enthalpy H (or internal energy U) of the system. In such a process, a closed system usually absorbs thermal energy from its surroundings, which is the heat transfer into the system. It may be a chemical process, such as dissolving ammonium nitrate in water, or a physical process, such as the melting of ice cubes.

Complete answer:
Whether a reaction can occur spontaneously depends not only on the enthalpy change but also on the entropy change (\[\Delta S\] ) and absolute temperature \[T\] . If a reaction is a spontaneous process at a certain temperature, the products have a lower Gibbs free energy \[G\; = \;H\; - \;TS\;\] than the reactants (an exergonic reaction), even if the enthalpy of the products is higher. According to the Le-chatelier’s principle, when the reaction is exothermic (change in enthalpy is negative and energy is released), heat is included as a product, and when the reaction is endothermic (change in enthalpy is positive and energy is consumed), heat is included as a reactant.
Hence, an endothermic reaction proceeds in the backward direction with decrease in temperature as according to the Le-chatelier’s principle, when any system at equilibrium for a long period of time is subjected to a change in concentration, temperature, volume, or pressure, the system changes to a new equilibrium, and this change partly counteracts the applied change.

Thus, the statement is false.

Note:
Thus, an endothermic process usually requires a favorable entropy increase (\[\Delta S\; > {\text{ }}0\] ) in the system that overcomes the unfavorable increase in enthalpy so that still \[\Delta G\; < {\text{ }}0\] . While endothermic phase transitions into more disordered states of higher entropy, e.g. melting and vaporization, spontaneous chemical reactions at moderate temperatures are rarely endothermic.