Chapter 17, Problem 47A

(a)

Interpretation Introduction

Interpretation:

The reaction is endothermic or exothermic is to be found.

Concept Introduction:

Endothermic reactions are those reactions in which heat is absorbed. The enthalpy change for the endothermic reaction is positive.

Exothermic reactions are those reactions in which heat is released. The enthalpy change for the endothermic reaction is negative.

Answer to Problem 47A

The given reaction will be exothermic.

Explanation of Solution

As it is given that when two substances in the glass beaker reacted, the beaker became too hot to touch. It means heat has been released when the two substances reacted, making the beaker absorb the released heat and thus, get hot.

(b)

Interpretation Introduction

Interpretation:

The surrounding for the given scenario is to be described.

Concept Introduction:

System is the part of the universe where observations are made and the remaining of the universe constitutes the surrounding.

Answer to Problem 47A

Beaker constitutes the surrounding.

Explanation of Solution

As it is given that the two substances react, they will be under observation and will constitute the system. The beaker which is the reaction vessel will constitute the surrounding. Energy transfer takes place between the system and the surrounding.