Chapter 7.1, Problem 7.2Q

(a)

Interpretation Introduction

Interpretation:

Given process below is exothermic or endothermic has to be given.

    $\text{S}(s)+{\text{O}}_{\text{2}}(g)\to {\text{SO}}_{\text{2}}(g),\Delta H=-71\text{kcal}$

Concept Introduction:

Chemical reaction may be described by the amount of heat that is released or absorbed.  The term that is used to represent the heat of the reaction is enthalpy and it is symbolized as $H$.  The energy difference between the reactants and the products in a chemical reaction is the change in enthalpy and it is symbolized as $\Delta H$.  In case of exothermic reaction, the energy released in the chemical reaction is represented using a negative sign before change in enthalpy and in case of endothermic reaction, the energy difference is represented using a positive sign.  Change in enthalpy can be represented in form of equation as,

    $A{H}_{reaction}=H_{\text{products}}-H_{\text{reactants}}$

(b)

Interpretation Introduction

Interpretation:

Given process below is exothermic or endothermic has to be given.

    ${\text{N}}_{\text{2}}(g)+2{\text{O}}_{\text{2}}(g)+16.2\text{kcal}\to {\text{2NO}}_{\text{2}}(g)$

Concept Introduction:

Refer part (a).