Question

Provide the formula for each of the following ternary oxyacids: (a) carbonic acid (b) nitrous acid

Short answer

(a) Carbonic acid: \( H_2CO_3 \); (b) Nitrous acid: \( HNO_2 \).

Step-by-step solution

Identify the Elements in the Oxyacids

Ternary oxyacids are acids composed of hydrogen, oxygen, and another element. In carbonic acid, the elements are hydrogen (H), carbon (C), and oxygen (O). In nitrous acid, the elements are nitrogen (N), hydrogen (H), and oxygen (O).

Recall Basic Oxyacid Formulas

The typical pattern for a ternary oxyacid is \( HXO_n \), where \( X \) is the central non-metal element and \( n \) depends on the particular acid. Carbonic acid typically has two oxygen atoms for every carbon atom and extra hydrogen atoms added to balance the charges. Nitrous acid follows a similar structure but for nitrogen.

Determine the Chemical Formula for Each Acid

For carbonic acid, the chemical formula is determined by the combination of one carbon atom, two oxygen atoms, and two hydrogen atoms, resulting in the formula \( H_2CO_3 \). Nitrous acid is comprised of one nitrogen atom, two oxygen atoms, and one hydrogen atom, thus its formula is \( HNO_2 \).

Key concepts

Chemical Formulas

Chemical formulas are like a recipe, showing how many of each type of atom combine to make a single molecule. For ternary oxyacids, these formulas are crucial because they reveal the standard pattern of formation.
For example, in the chemical formula of carbonic acid, represented as \( H_2CO_3 \), each part of the formula indicates a specific element and the number of atoms involved:

• H : Two hydrogen atoms (\( H_2 \))
• C : One carbon atom
• O : Three oxygen atoms

This precise construction forms the stable structure of the acid.
The chemical formula for nitrous acid, \( HNO_2 \), follows the same principle:

• H : One hydrogen atom
• N : One nitrogen atom
• O : Two oxygen atoms

This highlights the central element, nitrogen, and the extra oxygen required for its specific structure. Understanding chemical formulas helps clarify why certain elements are grouped, forming the core basis of tertiary oxyacids.

Hydrogen Bonds

Hydrogen bonds are a type of attractive interaction that occurs between molecules. In the structure of ternary oxyacids, hydrogen bonds play a crucial role. Even though the bonds within an individual molecule might not be traditional hydrogen bonds, their presence influences intermolecular interactions.
In carbonic acid and nitrous acid, the hydrogen atoms typically prefer being close to more electronegative oxygen atoms. These interactions create a form of attraction that imparts unique chemical properties to these acids.
Hydrogen bonding significantly affects:

• Acidity: The presence of hydrogen bonds can impact how easily an acid donates its hydrogen ion \((H^+)\), affecting its strength as an acid.
• Solubility: Increased hydrogen bonding typically enhances the solubility of oxyacids in water, a vital aspect for reactions in aqueous solutions.

This makes understanding hydrogen bonding essential for grasping the behavior of these acids in different environments.

Oxygen Atoms

Oxygen atoms are a key component in oxyacids, playing a primary role in shaping their structure and reactivity. In ternary oxyacids like carbonic and nitrous acids, oxygen is not just filler; it’s fundamental.
Each oxygen atom contributes significantly by forming bonds with both hydrogen and the central atom (either carbon in carbonic acid or nitrogen in nitrous acid). This forms an interconnected network within the acid molecule.
Oxygen atoms specifically impact:

• Acid strength: More oxygen in a molecule generally increases acid strength due to higher electronegativity, pulling electrons away from hydrogen and facilitating \(H^+\) donation.
• Resonance: Oxygen allows for resonance structures, which stabilize the molecule by distributing charge across the different atoms.

In essence, the role of oxygen atoms is to act as the connecting element that holds the molecule together, defining the acid’s properties and efficacy when in use.