Problem 87 - General Chemistry: Principles and Modern Applications

Question

One reaction for the production of adipic acid, \(\mathrm{HOOC}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{COOH},\) used in the manufacture of nylon, involves the oxidation of cyclohexanone, \(\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O},\) in a nitric acid solution. Assume that dinitrogen monoxide is also formed, and write a balanced equation for this reaction.

Step-by-Step Solution

Answer

The balanced chemical equation for the reaction is \(\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O} + 9\mathrm{H}_{2}\mathrm{O} + 51\mathrm{HNO}_{3} \rightarrow 6\mathrm{HOOC(CH}_{2}\mathrm{)_{4}COOH} + 51\mathrm{N}_{2} \mathrm{O}\).

Step 1: Write down the unbalanced equation

First, write down the unbalanced chemical reaction: \(\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O} + \mathrm{HNO}_{3} \rightarrow \mathrm{HOOC(CH}_{2}\mathrm{)_{4}COOH} + \mathrm{N}_{2} \mathrm{O}\).

Step 2: Balance the equation

Start by balancing the carbon atoms. There are 6 carbon atoms on the left side, therefore there should be 6 on the right side. However, there's only 1 atom in the adipic acid, which means multiply adipic acid by 6. Now balance the hydrogen atoms. On the left, there are 10, and on the right, there are 14 (from 6 adipic acid molecules and 2 from dinitrogen monoxide). Add 9 water molecules on the left to balance the hydrogen atoms. The equation now is \(\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O} + 9\mathrm{H}_{2}\mathrm{O} + \mathrm{HNO}_{3} \rightarrow 6\mathrm{HOOC(CH}_{2}\mathrm{)_{4}COOH} + 2\mathrm{N}_{2} \mathrm{O}\). Now, balance the oxygen atom: we have 1 (from cyclohexanone) + 18 (from water molecules) + 3 (from nitric acid) on the left, and 72 (from adipic acid) + 2 (from dinitrogen monoxide) on the right. Thus, we need 51 Nitric acid molecule on the left to balance the Oxygen atoms. The last step is balancing nitrogen atoms. We have 51 on the left (from nitric acid) and 2 on the right (from dinitrogen monoxide), add 49 dinitrogen monoxide on the right to balance. This gives the final balanced equation: \(\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O} + 9\mathrm{H}_{2}\mathrm{O} + 51\mathrm{HNO}_{3} \rightarrow 6\mathrm{HOOC(CH}_{2}\mathrm{)_{4}COOH} + 51\mathrm{N}_{2} \mathrm{O}\).

Step 3: Check the balanced equation

Always make sure to verify that all the atoms balance in the final equation. In this case, on both sides, there are 6 carbon atoms, 56 hydrogen atoms, and 102 oxygen atoms, and 51 nitrogen atoms. This confirms that the equation is balanced.

Key Concepts

Adipic Acid Production

Adipic acid is a critical compound primarily used in the production of nylon, which is a common material in textiles and plastics. The production process of adipic acid involves the use of cyclohexanone, a colorless organic compound, which is oxidized. This oxidation reaction is typically conducted in a nitric acid solution. During this process, dinitrogen monoxide, also known as laughing gas, is formed as a byproduct. Understanding this process is valuable as it outlines the conversion of raw materials into useful chemicals and explains how each component in the reaction contributes to producing adipic acid. This process also offers insight into environmentally considerate production methods, as managing byproducts like dinitrogen monoxide is crucial in limiting emissions.

Oxidation Reaction

Oxidation reactions are a fundamental part of chemical processes where a substance loses electrons. In the context of adipic acid production, cyclohexanone undergoes oxidation. This means it reacts with nitric acid, a powerful oxidizing agent, to form adipic acid. During this reaction, the cyclohexanone molecule gains oxygen atoms.
This process converts cyclohexanone into adipic acid by replacing certain hydrogen atoms with oxygen.

• Oxidation is critical in transforming organic compounds for industrial use.
• In adipic acid production, the reaction generates energy and additional byproducts.
• Handling these reactions is vital to maintaining safe and efficient industrial processes.

Understanding these reactions helps in optimizing industrial yields and minimizing waste, making production more sustainable.

Chemical Equation Balancing

Balancing chemical equations is crucial to accurately represent a chemical reaction. It ensures that the same number of each type of atom appears on both the reactant and product sides. In the exercise, the chemical equation features cyclohexanone reacting with nitric acid to produce adipic acid and dinitrogen monoxide.
Here are key steps to balance a chemical equation:

• Start by listing all reactants and products: Write down each compound's formula.
• Balance one element at a time: Begin with carbon, then hydrogen, and finish with oxygen.
• Check your work: Ensure the atom counts are equal on both sides to confirm balance.

For the given equation, adjustments were made to achieve a balanced formula: \[\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O} + 9\mathrm{H}_{2}\mathrm{O} + 51\mathrm{HNO}_{3} \rightarrow 6\mathrm{HOOC(CH}_{2}\mathrm{)_{4}COOH} + 51\mathrm{N}_{2} \mathrm{O}\] This practice exemplifies the law of conservation of mass and is essential for predicting reaction outcomes.