Question

On heating sodium metal in a current of dry ammonia, the compound formed is: (a) Sodium hydride (b) Sodium amide (c) Sodium azide (d) Sodium nitride

Short answer

Sodium amide is formed when sodium metal is heated in dry ammonia.

Step-by-step solution

Understand the Reaction

When sodium metal (Na) is heated in a current of dry ammonia (\( NH_3 \)), a specific reaction occurs between these two substances. The purpose is to determine what compound forms as a result of this reaction.

Identify the Possible Reaction

Sodium reacts with ammonia in a typical reaction to form sodium amide (\( NaNH_2 \)). This is known from inorganic chemistry, where alkali metals react with ammonia to form amides.

Confirm the Product

Upon reaction, sodium metal (\( 2Na \)) reacts with dry ammonia (\( 2NH_3 \)) to produce sodium amide (\( 2NaNH_2 \)) and hydrogen gas, as follows:\[2Na + 2NH_3 \rightarrow 2NaNH_2 + H_2\]This confirms that sodium amide is the primary product of this reaction.

Key concepts

Sodium Metal Reactions

Sodium metal is a highly reactive element and falls under the category of alkali metals in the periodic table. Its chemical symbol is Na. It is kept under oil or kerosene due to its rapid reaction with oxygen and moisture in the air. Sodium's reactivity is attributed to its single valence electron, which it tends to lose easily, forming positively charged ions. When sodium metal is exposed to substances like water or acids, it reacts vigorously, often releasing hydrogen gas and producing sodium hydroxide. This reactivity is also apparent when sodium is heated with other carefully controlled substances. Importantly, sodium reacts with ammonia to form compounds like sodium amide. To maintain a controlled environment, dry conditions are essential, preventing sodium's immediate reaction with atmospheric moisture. In summary,

• Sodium is highly reactive and kept under specific conditions to prevent unwanted reactions.
• Its single valence electron makes it prone to form positive ions easily.

Ammonia Reactions

Ammonia is a compound composed of nitrogen and hydrogen, represented by the chemical formula \( NH_3 \). It is a colorless gas with a distinct, pungent odor. Ammonia can act as a ligand, a base, or a possible reagent in various chemical reactions.In the context of sodium's reaction with ammonia, this compound serves as a reactant that facilitates the transformation of sodium into a more stable compound. Ammonia gas must be dry during this reaction to prevent interference from other substances that might disrupt the desired chemical process.When sodium is heated in dry ammonia:

• Ammonia acts as a reactant that aids in the formation of sodium amide.
• The reaction releases hydrogen gas as a byproduct.
• The dry nature of ammonia is crucial to achieve the correct outcome without unexpected moisture-induced reactions.

Sodium Amide Formation

Sodium amide (NaNH_2) is a compound that results when sodium reacts with ammonia under heated conditions. This chemical reaction is critical in inorganic chemistry due to the selective formation of sodium amide, which is widely used in industry and research settings.The reaction can be expressed in a balanced chemical equation:\[ 2Na + 2NH_3 \rightarrow 2NaNH_2 + H_2 \]Here, sodium metal interacts with ammonia, and through this process, sodium amide and hydrogen gas are formed. Sodium amide itself is a strong base and often used as a desiccant and a reagent for organic synthesis.Key points include:

• The reaction requires dry ammonia to prevent side reactions.
• Sodium amide works as a strong base in various chemical applications.
• The process naturally produces hydrogen gas as a byproduct.

Alkali Metal Chemistry

Alkali metals are a group of elements in the periodic table that include lithium, sodium, potassium, rubidium, cesium, and francium. These metals are known for their high reactivity, especially with water and halogens, forming caustic substances and other reactive compounds. In the world of inorganic chemistry, alkali metals engage in fascinating reactions due to their tendency to lose the outermost electron with ease, forming 1+ ions. This property results in bonds with various other elements, especially those that are electronegative. For example, when sodium, an alkali metal, reacts with dry ammonia:

• The electron transfer from sodium leads to the formation of stable compounds like sodium amide.
• The highly reactive nature of these metals requires controlled reaction conditions to manage safety and yields.
• This chemistry is not only fundamental but also extends to practical applications in synthesis and manufacturing.