Question

Consider the endothermic reaction: N2 (g) 2 H2 (g) → N2H4 (l) The entropy change of this reaction is ________ and the enthalpy change is ________, so at a very high temperature, this reaction is probably ________. Consider the endothermic reaction: N2 (g) 2 H2 (g) → N2H4 (l) The entropy change of this reaction is ________ and the enthalpy change is ________, so at a very high temperature, this reaction is probably ________. unfavorable; unfavorable; nonspontaneous unfavorable; favorable; spontaneous favorable; unfavorable; spontaneous favorable; unfavorable; nonspontaneous unfavorable; unfavorable; spontaneous

Answer 1

Answer: unfavourable, unfavourable, non spontaneous

Explanation:

Endothermic reactions are those in which heat is absorbed by the system and exothermic reactions are those in which heat is released by the system.

$\Delta H$ for Endothermic reaction is positive and  $\Delta H$ for Exothermic reaction is negative.

Entropy is the measure of randomness or disorder of a system. If a system moves from  an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

For the reaction:

$N_2(g)+2H_2(g)\rightarrow N_2H_4(l)$

$\Delta S$ is negative as the randomness decreases when gases convert into liquid.  

For reaction to be spontaneous, $\Delta G=-ve$ and favourable conditions are $\Delta H=-ve$ and $\Delta S=+ve$

Using Gibbs Helmholtz equation:

$\Delta G=\Delta H-T\Delta S$

$\Delta G=(+ve)-T(-ve)$

$\Delta G=(+ve)(+ve)$

$\Delta G=+ve$

Thus the reaction is non spontaneous at all temperatures.