Chapter 21, Problem 21.85QP

Interpretation Introduction

Interpretation:

The $\Delta \text{H}°$ for the roasting of galena, $\text{PbS}$ has to be calculated and also whether the reaction is endothermic or exothermic has to be given

Concept Introduction:

Enthalpy of reaction:

The enthalpy of a reaction is calculated by subtracting the heat of formation of reactatns from heat of formation of products.

$\Delta \text{H}°\text{ =}\sum \Delta \text{H}{°}_f{}_{\mathrm{Pr}\text{odcuts}}\text{ - }\sum \Delta \text{H}{°}_{f\text{ Reactants}}$

Exothermic and Endothermic Reaction:

Exothermic reaction is a reaction in which heat is given out to the surrounding from the system. $\Delta \text{H}°$ for an exothermic reaction will be negative.

Endothermic reaction is a reaction in which heat is gained by the system from the surrounding. $\Delta \text{H}°$ for an exothermic reaction will be positive.