Problem 61 - Chemistry The Central Science In Si Units

Question

Write a balanced equation for each of the following reactions: (a) preparation of white phosphorus from calcium phosphate, \((\mathbf{b})\) hydrolysis of \(\mathrm{PBr}_{3},(\mathbf{c})\) reduction of \(\mathrm{PBr}_{3}\) to \(\mathrm{P}_{4}\) in the gas phase, using \(\mathrm{H}_{2}\).

Step-by-Step Solution

Answer

(a) \(2 \text{Ca}_3(\text{PO}_4)_2 + 6 \text{SiO}_2 + 10 \text{C} \rightarrow 6 \text{CaSiO}_3 + 10 \text{CO} + \text{P}_4\); (b) \(\text{PBr}_3 + 3 \text{H}_2\text{O} \rightarrow \text{H}_3\text{PO}_3 + 3 \text{HBr}\); (c) \(4 \text{PBr}_3 + 6 \text{H}_2 \rightarrow \text{P}_4 + 12 \text{HBr}\).

Step 1: Write the chemical equation for the preparation of white phosphorus

To prepare white phosphorus, calcium phosphate is treated with silicon dioxide and coke at high temperature. This reaction can be represented as follows:\[ 2 ext{Ca}_3( ext{PO}_4)_2 + 6 ext{SiO}_2 + 10 ext{C} ightarrow 6 ext{CaSiO}_3 + 10 ext{CO} + ext{P}_4 \]

Step 2: Balance the equation for hydrolysis of \( \mathrm{PBr}_3 \)

In this reaction, phosphorus tribromide reacts with water to form phosphorous acid and hydrogen bromide. The balanced equation is:\[ \text{PBr}_3 + 3 \text{H}_2\text{O} \rightarrow \text{H}_3\text{PO}_3 + 3 \text{HBr} \]

Step 3: Write and balance the equation for reduction of \( \mathrm{PBr}_3 \) to \( \mathrm{P}_4 \)

Phosphorus tribromide is reduced by hydrogen gas to form white phosphorus and hydrogen bromide. The balanced chemical equation is:\[ 4 \text{PBr}_3 + 6 \text{H}_2 \rightarrow \text{P}_4 + 12 \text{HBr} \]

Key Concepts

Balancing Chemical Equations

Balancing chemical equations is a fundamental skill in chemistry that ensures mass conservation in chemical reactions. When a chemical reaction occurs, the quantity of each element must remain the same before and after the reaction. This involves adjusting coefficients - the numbers placed before molecules in the equations.

To successfully balance an equation, follow these steps:

• Write down the unbalanced equation.
• List the number of atoms for each element involved on both sides.
• Add coefficients to balance each element’s atoms.
• Ensure the same total number of each atom type is on both the reactant and product sides.
• Recheck the balance of all elements to verify.

It’s helpful to start with more complex molecules or elements appearing in just one reactant and one product. Balancing equations is an essential step to understanding and predicting the outcomes of chemical reactions.

Inorganic Chemistry

Inorganic chemistry focuses on the properties and behavior of inorganic compounds, which can range from metals, crystals, and minerals. It covers all elements other than carbon-based compounds, which are the domain of organic chemistry.

This branch of chemistry plays a critical role in the production of various everyday materials and pharmaceuticals. It has applications in catalysis and materials science, among others.

• Study the properties of elements like metals and non-metals.
• Understand how these elements interact with energy and each other to form compounds.
• Explore industrial applications and how inorganic reactions are used in creating products.

Comprehending inorganic chemistry involves recognizing patterns in chemical behaviors and reactions, making it crucial in bridging natural sciences and applied chemistry.

Phosphorus Reactions

Phosphorus is a versatile element that plays a vital role in many chemical reactions, especially in the field of inorganic chemistry. It can exist in several different forms, with white phosphorus being a common allotrope used in various reactions.

There are several key types of reactions phosphorus can undergo:

• Preparation: Involves converting compounds like calcium phosphate into usable phosphorus forms, which often requires reactions at high temperatures with other substances like silicon dioxide and coke.
• Hydrolysis: This is when phosphorus compounds like phosphorus tribromide react with water, resulting in products such as phosphorous acid and hydrogen bromide.
• Reduction: Through chemical reactions, phosphorus compounds can be reduced to different forms, such as the conversion of phosphorus tribromide into white phosphorus using hydrogen gas.

Understanding these reactions reveals phosphorus’s reactivity and provides insight into industrial processes and synthesis operations in chemistry.