Question

The temperature of water decreases on the dissolution of NH4NO3. From this observation, we can conclude that the solution process would be best described asa)exothermic with a positive entropy change.b)exothermic with a negative entropy change.c)endothermic with a negative entropy change.d)endothermic with a positive entropy change.e)exothermic with a negative free energy change

Answer 1

Answer: d)endothermic with a positive entropy change

Step-by-step 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.

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.

As temperature of water decreases on dissolution of
`NH_4NO_3` , it means heat has been absorbed by
`NH_4NO_3` during dissolution and that heat is taken from water. Thus process is endothermic. As dissolution will lead in the formation of ions
`NH_4^+` and
`NO_3^-` , randomness will increase and thus there is a positive entropy change.