Chapter 15: Problem 27
Suggest syntheses for each of the following from \(\mathrm{K}^{15} \mathrm{NO}_{3}\) (a) \(\mathrm{Na}^{15} \mathrm{NH}_{2},\) (b) \(^{15} \mathrm{N}_{2}\) and (c) \(\left[^{15} \mathrm{NO}\right]\left[\mathrm{AlCl}_{4}\right]\)
Short Answer
Expert verified
Transform \(\mathrm{K}^{15}\mathrm{NO}_3\) into \(\mathrm{H} ^{15}\mathrm{NO}_3\) for further conversion to \(\mathrm{Na}^{15}\mathrm{NH}_2\), \(\mathrm{^{15}N}_2\), and \(\left[^{15}\mathrm{NO}\right]\left[\mathrm{AlCl}_4\right]\).
Step by step solution
01
Understanding Starting Material Decomposition
The starting material is potassium nitrate, \(\mathrm{K}^{15}\mathrm{NO}_3\), which can decomposed into nitric acid \(\mathrm{H} ^{15}\mathrm{NO}_3\) by substituting the \(\mathrm{K}^+\) ion with the \(\mathrm{H}^+\) ion.
02
Synthesis of \\(\mathrm{Na}^{15} \mathrm{NH}_{2}\\) from \\(\mathrm{H}^{15}\mathrm{NO}_3\\)
Convert the \(\mathrm{H}^{15}\mathrm{NO}_3\) to \(\mathrm{^{15}NH}_3\) using a reducing agent such as metal hydride in the presence of a catalyst. Then, react \(\mathrm{^{15}NH}_3\) with sodium metal in a liquid ammonia environment to synthesize \(\mathrm{Na}^{15} \mathrm{NH}_{2}\).
03
Synthesis of \\(\mathrm{^{15}N}_2\\) from \\(\mathrm{H}^{15}\mathrm{NO}_3\\)
Decompose \(\mathrm{H}^{15}\mathrm{NO}_3\) to produce nitrous oxide (\(\mathrm{N}^{15}_2\mathrm{O}\)) using thermal decomposition. Use a higher temperature setting to create a condition where \(\mathrm{N}^{15}_2\mathrm{O}\) breaks into \(\mathrm{^{15}N}_2\) and \(\mathrm{^{15}O}\).
04
Synthesis of \\[^{15}\mathrm{NO}][\mathrm{AlCl}_4]\\ from \\(\mathrm{H}^{15}\mathrm{NO}_3\\)
Use \(\mathrm{H}^{15}\mathrm{NO}_3\) to prepare \([^{15}\mathrm{NO}]\) through partial reduction by a strong oxidizer like \(\mathrm{Cl}_2\). Then, treat it with anhydrous aluminum chloride in a suitable solvent like \(\mathrm{CH}_2\mathrm{Cl}_2\) to form \(\left[^{15}\mathrm{NO}\right]\left[\mathrm{AlCl}_4\right]\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Potassium Nitrate
Potassium nitrate, commonly known as saltpeter, has a chemical formula of \(\mathrm{KNO}_3\). It is a compound composed of potassium \(\mathrm{(K^+)}\), nitrogen \(\mathrm{(NO_3^-)}\), and oxygen atoms. Often used in fertilizers, fireworks, and food preservation, it also serves as a useful starting material in various chemical syntheses.
Potassium nitrate is highly soluble in water, allowing for easy manipulation in aqueous solutions. One critical aspect of \(\mathrm{KNO}_3\) is its ability to provide the nitrate ion \((\mathrm{NO_3^-})\), which can be transformed into other nitrogen-containing compounds.
By substituting the potassium ion \(\mathrm{K^+}\) with another cation like \(\mathrm{H^+}\), the nitrate can be converted into nitric acid \((\mathrm{HNO}_3)\), paving the way for further chemical transformations. This is particularly useful in isotope-labeled syntheses where the nitrogen atom has been labeled, such as \(\mathrm{K}^{15}\mathrm{NO}_3\).
Potassium nitrate is highly soluble in water, allowing for easy manipulation in aqueous solutions. One critical aspect of \(\mathrm{KNO}_3\) is its ability to provide the nitrate ion \((\mathrm{NO_3^-})\), which can be transformed into other nitrogen-containing compounds.
By substituting the potassium ion \(\mathrm{K^+}\) with another cation like \(\mathrm{H^+}\), the nitrate can be converted into nitric acid \((\mathrm{HNO}_3)\), paving the way for further chemical transformations. This is particularly useful in isotope-labeled syntheses where the nitrogen atom has been labeled, such as \(\mathrm{K}^{15}\mathrm{NO}_3\).
Ammonia Synthesis
Ammonia synthesis is a pivotal chemical process essential in producing fertilizers, explosives, and other chemical products. Ammonia, \(\mathrm{NH}_3\), is usually synthesized industrially through the Haber-Bosch process, which combines nitrogen and hydrogen gases under high temperatures and pressures in the presence of a catalyst.
In a lab setting, converting nitrate from potassium nitrate to ammonia involves reduction reactions. For instance, reducing \(\mathrm{H}^{15}\mathrm{NO}_3\) with a metal hydride catalyst can yield ammonia enriched with the \(^{15}\mathrm{N}\) isotope.
In a lab setting, converting nitrate from potassium nitrate to ammonia involves reduction reactions. For instance, reducing \(\mathrm{H}^{15}\mathrm{NO}_3\) with a metal hydride catalyst can yield ammonia enriched with the \(^{15}\mathrm{N}\) isotope.
- This conversion is crucial when designing isotopically labeled compounds for tracking chemical pathways or studying biological systems.
- Following reduction, ammonia can be reacted with sodium metal in liquid ammonia to form sodium amide \((\mathrm{Na}^{15}\mathrm{NH}_2)\), evidencing its versatile role in synthesis.
Thermal Decomposition
Thermal decomposition involves the breakdown of a compound through heat. This process is integral to many chemical reactions, especially where compounds are too stable to decompose via other means.
In the context of \(\mathrm{H}^{15}\mathrm{NO}_3\) conversion to nitrogen gas \(^{15}\mathrm{N}_2\), thermal decomposition facilitates the breakdown of nitric acid into nitrous oxide \((\mathrm{N}^{15}_2\mathrm{O})\).
In the context of \(\mathrm{H}^{15}\mathrm{NO}_3\) conversion to nitrogen gas \(^{15}\mathrm{N}_2\), thermal decomposition facilitates the breakdown of nitric acid into nitrous oxide \((\mathrm{N}^{15}_2\mathrm{O})\).
- Upon subjecting \(\mathrm{N}^{15}_2\mathrm{O}\) to elevated temperatures, further decomposition occurs, releasing \(^{15}\mathrm{N}_2\) gas alongside \(^{15}\mathrm{O}\).
- This process showcases the application of heat to drive otherwise non-spontaneous reactions.
Inorganic Chemistry Reactions
Inorganic chemistry deals with reactions involving inorganic compounds, which do not primarily contain carbon-hydrogen bonds. These reactions often require precise conditions, such as specific solvents, temperatures, or reactants.
For instance, synthesizing \([^{15}\mathrm{NO}][\mathrm{AlCl}_4]\) requires a combination of partial reduction and complexation reactions. The process begins with the partial reduction of \(\mathrm{H}^{15}\mathrm{NO}_3\) with a strong oxidizer like chlorine. This yields \([^{15}\mathrm{NO}]\), which is subsequently treated with anhydrous aluminum chloride.Using a solvent such as dichloromethane \((\mathrm{CH}_2\mathrm{Cl}_2)\), \([^{15}\mathrm{NO}]\) reacts with \(\mathrm{AlCl}_4^-\) to form the desired product.
For instance, synthesizing \([^{15}\mathrm{NO}][\mathrm{AlCl}_4]\) requires a combination of partial reduction and complexation reactions. The process begins with the partial reduction of \(\mathrm{H}^{15}\mathrm{NO}_3\) with a strong oxidizer like chlorine. This yields \([^{15}\mathrm{NO}]\), which is subsequently treated with anhydrous aluminum chloride.Using a solvent such as dichloromethane \((\mathrm{CH}_2\mathrm{Cl}_2)\), \([^{15}\mathrm{NO}]\) reacts with \(\mathrm{AlCl}_4^-\) to form the desired product.
- These reactions exemplify the precise conditions and reactivity principles that govern inorganic chemistry.
- Such processes illustrate how carefully controlled reactions and the use of catalysts can convert isotopically labelled starting materials into valuable chemical products.