Problem 17 - Chemistry in 30 days

Question

Oxidation number of \(\mathrm{N}\) in \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) is (a) \(-3\) (b) \(+5\) (c) \(-3\) and \(+5\)

Step-by-Step Solution

Answer

The oxidation numbers of \(\mathrm{N}\) in \(\mathrm{NH}_4\mathrm{NO}_3\) are \(-3\) and \(+5\).

Step 1: Understand the Compound

The compound in question is ammonium nitrate, \ \( \mathrm{NH}_4 \mathrm{NO}_3 \). This compound contains two different nitrogen atoms, one in the ammonium ion (\( \mathrm{NH}_4^+ \)) and one in the nitrate ion (\( \mathrm{NO}_3^- \)). Each nitrogen can potentially have a different oxidation state.

Step 2: Oxidation State of Nitrogen in \( \mathrm{NH}_4^+ \)

For the ammonium ion, \( \mathrm{NH}_4^+ \), we assume the oxidation state of hydrogen is \(+1\), as it is typically in most compounds. Let \( x \) be the oxidation state of nitrogen in \( \mathrm{NH}_4^+ \). The formula for the charge balance in the ion is: \ \[ x + 4(+1) = +1 \] Solving for \( x \): \ \[ x + 4 = 1 \] \ \[ x = -3 \] Thus, the oxidation state of nitrogen in \( \mathrm{NH}_4^+ \) is \(-3\).

Step 3: Oxidation State of Nitrogen in \( \mathrm{NO}_3^- \)

In the nitrate ion, \( \mathrm{NO}_3^- \), oxygen typically has an oxidation state of \(-2\). Let \( y \) be the oxidation state of nitrogen in \( \mathrm{NO}_3^- \). The formula for the charge balance in the ion is: \ \[ y + 3(-2) = -1 \] Solving for \( y \): \ \[ y - 6 = -1 \] \ \[ y = +5 \] Thus, the oxidation state of nitrogen in \( \mathrm{NO}_3^- \) is \(+5\).

Step 4: Conclusion

Based on our calculations, the oxidation states of nitrogen in \( \mathrm{NH}_4 \mathrm{NO}_3 \) are \(-3\) for the ammonium ion and \(+5\) for the nitrate ion. This corresponds to option (c) in the question.

Key Concepts

Ammonium Nitrate

Ammonium nitrate, with the chemical formula \( \mathrm{NH}_4\mathrm{NO}_3 \), is a fascinating compound because it incorporates two distinctive types of nitrogen ions. This aspect makes it essential in various applications such as fertilizers and explosives.

• The ammonium ion, represented as \( \mathrm{NH}_4^+ \), consists of nitrogen bonded to four hydrogen atoms.
• The nitrate ion, symbolized by \( \mathrm{NO}_3^- \), features nitrogen bonded to three oxygen atoms.

Each nitrogen atom in ammonium nitrate carries a different oxidation state, which is a pivotal feature when studying chemical reactions and behaviors. Learning how to determine these oxidation states is crucial for students delving into chemistry.

Oxidation State Calculation

Calculating oxidation states is about understanding the charge each atom would have if all bonds were 100% ionic. This principle allows scientists to determine electron distributions in compounds. Here's a simple guide on how to compute these states:

• Assign oxidation states based on common charge conventions: for instance, hydrogen is generally \(+1\) and oxygen \(-2\).
• Formulate an equation based on these assignments to balance the compound or ion charge.
• Solve the equation to find the unknown oxidation state of the atom in question.

For example, in the ammonium ion \( \mathrm{NH}_4^+ \), assume hydrogen is \(+1\). Using the equation \( x + 4(+1) = +1 \), we find that nitrogen has an oxidation state of \(-3\). Similarly, in the nitrate ion \( \mathrm{NO}_3^- \), oxygen is \(-2\), leading to the equation \( y + 3(-2) = -1 \), making nitrogen \(+5\). These systematic methods help in predicting reactions and bonding structures.

Chemical Compounds

Chemical compounds are substances formed by the joining of two or more different elements in fixed proportions. These compounds have unique properties, distinct from their individual constituent elements.

• Compounds are held together by chemical bonds. These could be ionic, covalent, or metallic bonds, depending on the involved elements.
• The ratios between elements in a compound are always fixed. Hence, every molecule of a compound like water \(H_2O\) always contains two hydrogen atoms for each oxygen atom.

Understanding chemical compounds requires insight into how atoms combine and interact, generally determined by the oxidation states. This knowledge provides a foundational understanding that is crucial in all chemical education.

Nitrogen in Chemistry

Nitrogen is a versatile element essential to life and biochemical processes. Its place in the periodic table allows it to form various stable bonds, making it integral in both organic and inorganic chemistry.

• Nitrogen typically forms three bonds, but it can work in diverse coordination environments, appearing in forms like \( \mathrm{N}_2 \) and multiple solid-state structures.
• In compounds, nitrogen's oxidation state can range from \(-3\) to \(+5\), giving it extensive functionality in chemical reactions.
• Its presence is crucial in amino acids, nucleic acids, and other biological molecules.

The role of nitrogen in chemistry is vast, covering areas from agriculture through fertilizers, like ammonium nitrate, to explosives and environmental science. Understanding its oxidation states and behavior in compounds is a fundamental skill for chemistry students.