Chapter 21, Problem 21.40SP

Interpretation Introduction

Interpretation:

Using the standard enthalpy and free energy values, calculate the standard values for enthalpy and free energy of the roasting of ZnS. Explain why the values for the standard enthalpy and free energy are different and explain the sign of (?H° - ?G°).

Concept introduction:

• An ore is a complex mixture of metal-containing mineral and economically worthless material called gangue, consisting of sand, clay, and other impurities.
• Extracting a metal from its ore requires three main steps: (1) concentration of the ore, and if necessary, chemical treatment prior to reduction; (2) reduction of the mineral to the free metal; (3) refining or purification of the metal.
• Roasting is the process of heating the sulfide minerals in air (O₂) to form metal-oxides

To classify:Each balanced equation.