Ammonium nitrate, NH4NO3, is used in “cold packs”. Which statement best describes why the products are favored, when the solid is mixed with water?
NH4NO3(s) → NH4+ (aq) + NO3- (aq)
A) Heat is transferred to the surroundings to lower the temperature and the entropy change is positive.
B)The kinetic energy of the products decreases and the entropy change is positive.
C)The enthalpy change is positive and the entropy change is negative.
D)The potential energy of the products is more negative and the entropy change is positive.
I would look at D
To determine the correct answer, we need to understand the changes in enthalpy and entropy that occur when ammonium nitrate (NH4NO3) is dissolved in water.
Enthalpy is a measure of the heat absorbed or released during a chemical reaction, while entropy is a measure of the disorder or randomness of a system.
By examining the given reaction, we can see that the solid ammonium nitrate (NH4NO3(s)) dissociates into its ions, NH4+ (aq) and NO3- (aq), when mixed with water.
Option A suggests that heat is transferred to the surroundings to lower the temperature and the entropy change is positive. However, in this case, heat is actually absorbed from the surroundings, leading to a temperature increase and a decrease in entropy.
Option B suggests that the kinetic energy of the products decreases and the entropy change is positive. However, the dissolution of ammonium nitrate actually increases the kinetic energy of the products, as the ions become free to move and disperse within the water, contributing to an increase in entropy.
Option C suggests that the enthalpy change is positive and the entropy change is negative. Enthalpy change refers to the heat absorbed or released during a reaction, and in this case, the dissolution of ammonium nitrate is exothermic, meaning it releases heat and has a negative enthalpy change. Additionally, the dissolution leads to an increase in disorder and randomness, resulting in a positive entropy change.
Option D suggests that the potential energy of the products is more negative and the entropy change is positive. While the potential energy of the products is indeed more negative than that of the reactant, this does not contribute to why the products are favored when ammonium nitrate is mixed with water. Moreover, as mentioned earlier, the dissolution of ammonium nitrate results in an increase in entropy.
Based on the explanation, the correct answer is option B) The kinetic energy of the products decreases and the entropy change is positive.