Chapter 10, Problem 29A

Interpretation Introduction

Interpretation:Whether the given reaction is endothermic or exothermic to bedescribed. 

  ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}\left(aq\right)\to 2{\text{C}}_2{\text{H}}_5\text{OH}\left(aq\right)+2{\text{CO}}_{\text{2}}\left(g\right)$

Concept introduction:The term $\text{U+PV}$ is known as enthalpy of the system. It is indicated by H. It performs total energy stored in the system. Thus,

  $\text{H=U+PV}$

Here U, P and V are definite quantities.

Answer to Problem 29A

The reaction is exothermic and energy is released in form of heat.

Explanation of Solution

The given equation is as follows:

  ${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}\left(aq\right)\to 2{\text{C}}_2{\text{H}}_5\text{OH}\left(aq\right)+2{\text{CO}}_{\text{2}}\left(g\right)$

Enthalpy change for reaction is given by -67kJ.

In exothermic reaction, enthalpy change is a negative number. Because in this reaction, enthalpy is movedfrom the system. Thus the reaction is exothermic in nature. Thus energy is released in form of heat.

Conclusion

Products of exothermic reactions are hotter than reactant. Fire transfers energy in form of heat and light. Thus fire is an exothermic reaction.