Problem 90 - Chemistry and Chemical Reactivity

Question

Consider the chemistries of \(\mathrm{C}, \mathrm{Si}, \mathrm{Ge},\) and \(\mathrm{Sn}\). (a) Write a balanced chemical equation to depict the reaction of each element with elemental chlorine. (b) Describe the bonding in each of the products of the reactions with chlorine as ionic or covalent. (c) Compare the reactions, if any, of some Group 4A chlorides - \(\mathrm{CCl}_{4}, \mathrm{SiCl}_{4}\), and \(\mathrm{SnCl}_{4}-\) with water.

Step-by-Step Solution

Answer

CCl extsubscript{4} is inert with water; SiCl extsubscript{4} and SnCl extsubscript{4} react forming acids.

Step 1: Write Balanced Chemical Equations

For each element (C, Si, Ge, Sn) reacting with chlorine (Cl), we need to write a balanced chemical equation. 1. **Carbon:** \[ \text{C} + 2\text{Cl}_2 \rightarrow \text{CCl}_4 \] 2. **Silicon:** \[ \text{Si} + 2\text{Cl}_2 \rightarrow \text{SiCl}_4 \] 3. **Germanium:** \[ \text{Ge} + 2\text{Cl}_2 \rightarrow \text{GeCl}_4 \] 4. **Tin:** \[ \text{Sn} + 2\text{Cl}_2 \rightarrow \text{SnCl}_4 \] These equations are balanced as the number of each type of atom is the same on both sides of the reaction.

Step 2: Determine the Bonding Type

We will now identify the type of bonding in each of these chlorides. - **CCl extsubscript{4}:** Carbon tetrachloride has covalent bonds since both carbon and chlorine are nonmetals that share electrons. - **SiCl extsubscript{4}:** Silicon tetrachloride also features covalent bonding due to similar nonmetal interactions. - **GeCl extsubscript{4}:** Germanium, similar to silicon, forms covalent bonds with chlorine. - **SnCl extsubscript{4}:** Tin can form covalent bonds with chlorine, although the bonding can have partial ionic character due to the metallic nature of tin. However, it is often regarded as predominantly covalent.

Step 3: Compare Reactions with Water

Examine the reactions of - **CCl extsubscript{4}:** Carbon tetrachloride does not react with water as it is an inert, non-polar compound.- **SiCl extsubscript{4}:** Silicon tetrachloride reacts rapidly with water, undergoing hydrolysis to form silicic acid and hydrogen chloride: \[ \text{SiCl}_4 + 2\text{H}_2\text{O} \rightarrow \text{SiO}_2 \cdot x\text{H}_2\text{O} + 4\text{HCl} \]- **SnCl extsubscript{4}:** Tin tetrachloride reacts with water to produce tin(IV) oxide and hydrochloric acid: \[ \text{SnCl}_4 + 2\text{H}_2\text{O} \rightarrow \text{SnO}_2 + 4\text{HCl} \] Thus, while SiCl extsubscript{4} and SnCl extsubscript{4} react with water, CCl extsubscript{4} does not.

Key Concepts

Covalent Bonding in Group 4A Elements

Covalent bonding occurs when atoms share electrons to form a stable configuration. In Group 4A elements like Carbon (C), Silicon (Si), Germanium (Ge), and Tin (Sn), covalent bonds are key in forming compounds with chlorine.

In carbon tetrachloride (\(\text{CCl}_4\)), each carbon atom forms four covalent bonds with chlorine atoms. This sharing of electrons allows both atoms to achieve a full outer shell.

• **Hydrocarbons like \(\text{CCl}_4\) are non-polar and usually do not conduct electricity.**
• **Silicon and germanium form similar covalent bonds with chlorine, represented by \(\text{SiCl}_4\) and \(\text{GeCl}_4\).**

Tin, while being more metallic, still forms mainly covalent bonds as seen in tin tetrachloride (\(\text{SnCl}_4\)). This tendency can be attributed to the relatively high electronegativity difference, promoting electron sharing.

Understanding Chemical Equations

A chemical equation illustrates the transformation of reactants into products. It must be balanced, meaning the number of atoms for each element is equal on both sides.

For the reaction of Group 4A elements with chlorine, the balanced equations are:

• **Carbon: \(\text{C} + 2\text{Cl}_2 \rightarrow \text{CCl}_4\)**
• **Silicon: \(\text{Si} + 2\text{Cl}_2 \rightarrow \text{SiCl}_4\)**
• **Germanium: \(\text{Ge} + 2\text{Cl}_2 \rightarrow \text{GeCl}_4\)**
• **Tin: \(\text{Sn} + 2\text{Cl}_2 \rightarrow \text{SnCl}_4\)**

These equations show the stoichiometric relationships, where a single molecule of the element reacts with two molecules of chlorine to form the tetrachloride. This balance is crucial for understanding the reaction's quantitative aspects.

Hydrolysis Reactions of Group 4A Chlorides

Hydrolysis involves a reaction with water, leading to the breakdown of a compound. In our context, we examine how \(\text{CCl}_4\), \(\text{SiCl}_4\), and \(\text{SnCl}_4\) react with water.

- **Carbon Tetrachloride** is resistant to hydrolysis. Being non-polar, it doesn't interact with water.
- **Silicon Tetrachloride** undergoes hydrolysis to form silicic acid and hydrogen chloride:\[\text{SiCl}_4 + 2\text{H}_2\text{O} \rightarrow \text{SiO}_2 \cdot x\text{H}_2\text{O} + 4\text{HCl}\]
- **Tin Tetrachloride** reacts with water producing tin(IV) oxide and hydrochloric acid:\[\text{SnCl}_4 + 2\text{H}_2\text{O} \rightarrow \text{SnO}_2 + 4\text{HCl}\]

Hydrolysis leads to breakdown and formation of new compounds, transforming chlorides into acids or oxides.