Problem 15 - Chemistry in 30 days

Question

\(\mathrm{NaNO}_{3}\) on being heated to \(500^{\circ} \mathrm{C}\) gives (a) \(\mathrm{NaNO}_{2}\) only (b) \(\mathrm{Na}_{2} \mathrm{O}+\mathrm{N}_{2}\) (c) \(\mathrm{NaNO}_{2}+\mathrm{O}_{2}\) (d) \(\mathrm{NaNO}_{2}+\mathrm{O}_{2}+\mathrm{N}_{2}\)

Step-by-Step Solution

Answer

(c) \(\mathrm{NaNO}_{2} + \mathrm{O}_{2}\) is the correct option.

Step 1: Identify the Reactant

The reactant in this problem is sodium nitrate, represented by the chemical formula \(\mathrm{NaNO}_{3}\). We need to determine what happens to this compound when it is heated to \(500^{\circ}C\).

Step 2: Predict the Decomposition Reaction

When \(\mathrm{NaNO}_{3}\) is heated, it undergoes a decomposition reaction. This typically results in the formation of sodium nitrite (\(\mathrm{NaNO}_{2}\)) and oxygen gas (\(\mathrm{O}_{2}\)). The balanced chemical equation for this reaction is:\[ 2\mathrm{NaNO}_{3} \rightarrow 2\mathrm{NaNO}_{2} + \mathrm{O}_{2} \]

Step 3: Compare with Options

From the balanced chemical equation, the decomposition of \(\mathrm{NaNO}_{3}\) when heated results in \(\mathrm{NaNO}_{2}\) and \(\mathrm{O}_{2}\). This matches one of the given options precisely.

Step 4: Select the Correct Option

Option (c) is: \(\mathrm{NaNO}_{2} + \mathrm{O}_{2}\), which matches our predicted products from the reaction of heating \(\mathrm{NaNO}_{3}\). Therefore, option (c) is the correct answer.

Key Concepts

Understanding Sodium Nitrate

Sodium nitrate is a chemical compound with the formula \(\text{NaNO}_3\). It is a white, water-soluble salt commonly used in fertilizers, explosives, and as a food preservative.
Sodium nitrate is an ionic compound made up of sodium cations \((\text{Na}^+)\) and nitrate anions \((\text{NO}_3^-)\). The nitrate ions are what make it reactive under certain conditions, such as heating.
Upon heating, sodium nitrate can decompose into other substances, showcasing its chemical activity. This decomposition process is important in various industrial applications and plays a crucial role in understanding basic chemistry concepts.

Introduction to Chemical Reactions

Chemical reactions occur when substances interact to form new products. These interactions can lead to changes in the properties of the original substances.
There are many types of chemical reactions, including decomposition, synthesis, combustion, and replacement reactions. A chemical reaction is usually characterized by a change in temperature, color, gas production, or the formation of a precipitate.
In the case of sodium nitrate, when it is heated, it undergoes a decomposition reaction. This means the compound breaks down into simpler substances. Understanding reactions like this helps us predict the behavior of substances under different conditions.

Balancing Chemical Equations

Balancing chemical equations is a fundamental skill in chemistry. It ensures that the number of atoms of each element is equal on both sides of the reaction. This reflects the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.
In the decomposition of sodium nitrate, the balanced equation is \[2\text{NaNO}_3 \rightarrow 2\text{NaNO}_2 + \text{O}_2\]. Here, we see two molecules of sodium nitrate decompose to form two molecules of sodium nitrite and one molecule of oxygen gas.

• Ensure each element has the same number of atoms on both sides.
• Use whole numbers as coefficients.
• Double-check your balanced equation to confirm accuracy.

Mastering this technique is crucial for accurately representing chemical reactions.

Exploring Thermal Decomposition

Thermal decomposition is a type of chemical reaction where a compound breaks down into simpler substances when heated. This process usually requires a certain amount of energy in the form of heat.
Sodium nitrate undergoes thermal decomposition when heated to about \(500^{\circ}\text{C}\). The heat energy helps to break the chemical bonds in sodium nitrate, forming sodium nitrite and oxygen gas.

• Energy is absorbed to break the atomic bonds.
• New substances form as a result of the decomposition.

This type of reaction is a clear example of how heat can influence the stability and composition of compounds, providing insights into how substances behave under different thermal conditions.