Question

Write a proper formation reaction for each substance. a) \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{~s})\) b) \(\mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{~s})\) c) \(\mathrm{Al}(\mathrm{OH})_{3}(\mathrm{~s})\)

Short answer

Formation reactions are balanced equations that form 1 mole of a compound from its elements in their standard states.

Step-by-step solution

Understand Formation Reactions

A formation reaction involves forming 1 mole of a compound from its elements in their standard states. Standard states refer to the most stable forms of the elements at 1 atm pressure and 25°C.

Write Formation Reaction for \\(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{~s})\\)

Identify the elements in \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{~s})\): Carbon (C), Hydrogen (H), and Oxygen (O). In their standard states, Carbon is \(\mathrm{C}(\mathrm{s})\), Hydrogen is \(\mathrm{H}_{2}(\mathrm{g})\), and Oxygen is \(\mathrm{O}_{2}(\mathrm{g})\). Balance the reaction: \[12 \mathrm{C}(\mathrm{s}) + 11 \mathrm{H}_{2}(\mathrm{g}) + 5.5 \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{~s})\] This shows the formation of 1 mole of sucrose from its elements.

Write Formation Reaction for \\( \mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{~s}) \\)

Identify the elements: Zinc (Zn), Nitrogen (N), and Oxygen (O). Their standard states are \(\mathrm{Zn}(\mathrm{s})\), \(\mathrm{N}_{2}(\mathrm{g})\), and \(\mathrm{O}_{2}(\mathrm{g})\). Balance the reaction: \[\mathrm{Zn}(\mathrm{s}) + \mathrm{N}_{2}(\mathrm{g}) + 3 \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{~s})\] This shows the formation of 1 mole of zinc nitrate from its elements.

Write Formation Reaction for \\(\mathrm{Al}(\mathrm{OH})_{3}(\mathrm{~s})\\)

Identify the elements: Aluminum (Al), Oxygen (O), and Hydrogen (H). Their standard states are \(\mathrm{Al}(\mathrm{s})\), \(\mathrm{O}_{2}(\mathrm{g})\), and \(\mathrm{H}_{2}(\mathrm{g})\). Balance the reaction: \[\mathrm{Al}(\mathrm{s}) + \frac{3}{2} \mathrm{O}_{2}(\mathrm{g}) + \frac{3}{2} \mathrm{H}_{2}(\mathrm{g}) \rightarrow \mathrm{Al}(\mathrm{OH})_{3}(\mathrm{~s})\] This shows the formation of 1 mole of aluminum hydroxide from its elements.

Key concepts

Standard States

Standard states are critical when discussing formation reactions in chemistry. Each element has a standard state, which is its most stable physical form under standard conditions. These conditions are at a pressure of 1 atmosphere and a temperature of 25 degrees Celsius. For example, the standard state of carbon is graphite, denoted as \( \mathrm{C}(\mathrm{s}) \). Similarly, hydrogen is \( \mathrm{H}_{2}(\mathrm{g}) \) and oxygen is \( \mathrm{O}_{2}(\mathrm{g}) \). Recognizing these standard states is vital for writing formation reactions because these reactions illustrate how a compound is produced directly from its element's standard forms.
Standard states help provide a baseline or reference point for understanding energy changes in reactions. This is valuable, especially when measuring enthalpy changes, as it allows chemists to create uniform data comparison across different compounds. Understanding these states ensures the comprehension of reactions' efficiency and sustainability in real-world applications.

Balancing Chemical Equations

Balancing chemical equations is a crucial step in writing formation reactions. It ensures that the number of each type of atom on the reactant side equals the number on the product side.
To balance an equation, follow these steps:

• List each element and count atoms on both sides of the equation.
• Adjust coefficients before formulas (not subscripts) to balance each element.
• Start with elements that appear in a single compound on each side.
• Leave complex molecules and single-element gases, such as \( \mathrm{O}_{2} \) or \( \mathrm{N}_{2} \), for last.

Taking the formation of aluminum hydroxide, \( \mathrm{Al}(\mathrm{OH})_{3} \), as an example, it involves balancing the equation:\[ \mathrm{Al}(\mathrm{s}) + \frac{3}{2} \mathrm{O}_{2}(\mathrm{g}) + \frac{3}{2} \mathrm{H}_{2}(\mathrm{g}) \rightarrow \mathrm{Al}(\mathrm{OH})_{3}(\mathrm{~s}) \]By understanding these principles, students can accurately represent the formation of compounds, ensuring they meet the conservation of mass.

Compound Synthesis

Compound synthesis through formation reactions is about creating a desired compound from its elemental components. A formation reaction is a specific kind of synthesis reaction where 1 mole of a compound is formed directly from its elements in their standard states. This way, it's possible to predict the yield and efficiency of producing compounds.
Consider the example of synthesizing sucrose, \( \mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{~s}) \). Here, carbon, hydrogen, and oxygen are combined:\[ 12 \mathrm{C}(\mathrm{s}) + 11 \mathrm{H}_{2}(\mathrm{g}) + 5.5 \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{~s}) \]By understanding the chemical properties and standard states of the elements involved, chemists can predict the products and conditions required for synthesis.
This understanding directly relates to designing processes that minimize waste and energy use, which is significant in both industrial applications and academic research.