Chapter 17.1, Problem 2SP

Interpretation Introduction

Interpretation: The reaction of barium hydroxide octahydrate with ammonium thiocyanate is endothermic or exothermic is to be found.

Concept introduction: The system is the part of the universe that is taken under consideration.

Surroundings are the remaining portion of the universe excluding the system.

An endothermic process is one in which heat is absorbed by the system. Thus, the direction of the heat flow is from the surroundings to the system.

An exothermic process is one in which heat is released by the system. Thus, the direction of the heat flow is from the system to the surroundings.

Answer to Problem 2SP

The reaction of barium hydroxide octahydrate, ${\text{Ba(OH)}}_{\text{2}}{\text{.8H}}_{\text{2}}\text{O}$ with ammonium thiocyanate, ${\text{NH}}_{\text{4}}\text{SCN}$ is endothermic.

Explanation of Solution

During the reaction of barium hydroxide octahydrate, ${\text{Ba(OH)}}_{\text{2}}{\text{.8H}}_{\text{2}}\text{O}$ with ammonium thiocyanate, ${\text{NH}}_{\text{4}}\text{SCN}$ the beaker becomes cold which means the heat has flown out of the beaker, and thus, the direction of heat flow is from the surrounding to the system. Thus, the reaction is endothermic.

Conclusion

Thus, the reaction of barium hydroxide octahydrate, $Ba{\left(OH\right)}_2.8H_{2}O$ with ammonium thiocyanate ${\text{NH}}_{\text{4}}\text{SCN}$ is endothermic.