Problem 90 - Chemistry: The Central Science

Question

Ultrapure germanium, like silicon, is used in semiconductors. Germanium of "ordinary" purity is prepared by the high-temperature reduction of \(\mathrm{GeO}_{2}\) with carbon. The Ge is converted to \(\mathrm{GeCl}_{4}\) by treatment with \(\mathrm{Cl}_{2}\) and then purified by distillation; \(\mathrm{GeCl}_{4}\) is then hydrolyzed in water to \(\mathrm{GeO}_{2}\) and reduced to the elemental form with \(\mathrm{H}_{2}\). The element is then zone refined. Write a balanced chemical equation for each of the chemical transformations in the course of forming ultrapure Ge from \(\mathrm{GeO}_{2}\).

Step-by-Step Solution

Answer

The balanced chemical equations for the various steps involved in preparing ultrapure germanium (Ge) from germanium dioxide (GeO₂) are as follows: 1. Reduction of GeO₂ with carbon (C): \(GeO_{2} + C \rightarrow Ge + CO_{2}\) 2. Conversion of Ge to GeCl₄ using Cl₂: \(Ge + 2 Cl_{2} \rightarrow GeCl_{4}\) 4. Hydrolysis of GeCl₄ in water: \(GeCl_{4} + 2 H_{2}O \rightarrow GeO_{2} + 4 HCl\) 5. Reduction of GeO₂ with H₂: \(GeO_{2} + 2 H_{2} \rightarrow Ge + 2 H_{2}O\)

Step 1: Reduction of GeO₂ with Carbon

To reduce germanium dioxide (GeO₂) with carbon (C), we can use the following balanced chemical equation: \[GeO_{2} + C \rightarrow Ge + CO_{2}\]

Step 2: Conversion of Ge to GeCl₄ using Cl₂

To convert germanium (Ge) to germanium tetrachloride (GeCl₄) using chlorine (Cl₂), we can use the following balanced chemical equation: \[Ge + 2 Cl_{2} \rightarrow GeCl_{4}\]

Step 3: Purification of GeCl₄ by distillation

The purification of GeCl₄ by distillation is a physical process, not a chemical reaction. Therefore, no chemical equation is needed for this step.

Step 4: Hydrolysis of GeCl₄ in water

To hydrolyze germanium tetrachloride (GeCl₄) in water (H₂O), we can use the following balanced chemical equation: \[GeCl_{4} + 2 H_{2}O \rightarrow GeO_{2} + 4 HCl\]

Step 5: Reduction of GeO₂ with H₂

To reduce germanium dioxide (GeO₂) with hydrogen gas (H₂), we can use the following balanced chemical equation: \[GeO_{2} + 2 H_{2} \rightarrow Ge + 2 H_{2}O\]