Chapter 21, Problem 72QAP

Interpretation Introduction

Interpretation:

The cost of HF needed to extract gold from the given reaction needs to be compared with the cost of gold formed.

Concept introduction:

Quartz is used to extract gold with HF. Here, the reaction between HF and quartz forms silicon tetrafluoride and water. The balance chemical reaction can be written as follows:

$\text{4 HF(}aq{\text{)+ SiO}}_{\text{2}}\text{(}aq\text{)}\to {\text{SiF}}_{\text{4}}\text{(}aq{\text{)+ 2 H}}_{\text{2}}\text{O}\left(l\right)$