Question

Sulfuric acid is a dehydrating agent. Write balanced equations for the reactions between sulfuric acid and (a) HCOOH, the following substances: (b) \(\mathrm{H}_{3} \mathrm{PO}_{4}\) (c) \(\mathrm{HNO}_{3}\), (d) \(\mathrm{HClO}_{3}\). (Hint: Sulfuric acid is not decomposed by the dehydrating action.)

Short answer

Balanced equations show dehydrating actions: HCOOH to CO and water, H3PO4 to HPO3 and water, 2 HNO3 to NO2, water, and 1/2 O2, and 2 HClO3 to ClO2, water, and 1/2 O2.

Step-by-step solution

Understand the Role of Sulfuric Acid

Sulfuric acid acts as a dehydrating agent, meaning it removes water molecules from compounds. In chemical reactions involving other acids, it can strip water away, potentially leading to the formation of anhydrides or decomposing substances into their gaseous components.

Reaction with Formic Acid (HCOOH)

When sulfuric acid reacts with formic acid (HCOOH), it dehydrates the formic acid. The balanced chemical reaction is: \[ \text{HCOOH} ightarrow \text{CO} + \text{H}_2\text{O} \]. This reaction primarily leads to the production of carbon monoxide and water.

Reaction with Phosphoric Acid (H3PO4)

For phosphoric acid, sulfuric acid can dehydrate it to form metaphosphoric acid (HPO3). The reaction is: \[ \text{H}_3\text{PO}_4 \rightarrow \text{HPO}_3 + \text{H}_2\text{O} \]. This showcases the removal of water by sulfuric acid, leading to an unstable compound if heated further.

Reaction with Nitric Acid (HNO3)

Nitric acid decomposes under sulfuric acid's dehydrating action. The reaction results in nitrogen dioxide and water: \[ \text{2 HNO}_3 \rightarrow \text{2 NO}_2 + \text{H}_2\text{O} + \text{1/2 O}_2 \]. These are further released as gases.

Reaction with Chloric Acid (HClO3)

Chloric acid, upon dehydration by sulfuric acid, decomposes to form chlorine dioxide, water, and oxygen. The balanced equation is: \[ \text{2 HClO}_3 \rightarrow \text{2 ClO}_2 + \text{H}_2\text{O} + \text{1/2 O}_2 \]. Sulfuric acid facilitates the release of water and decomposition.

Key concepts

Sulfuric Acid

Sulfuric acid is a highly corrosive, dense liquid that serves many purposes in chemistry, particularly as a dehydrating agent. A dehydrating agent is a substance that can remove water (H₂O) from other compounds. This ability makes sulfuric acid exceptionally useful in various chemical reactions.

• It has the chemical formula H₂SO₄.
• It is strong, providing both acidity and the ability to dehydrate substances.

Sulfuric acid not only desiccates compounds but also absorbs moisture from the air. When used to dehydrate, it changes the structure of the compounds by removing water molecules. In laboratory settings, sulfuric acid’s dehydrating properties are harnessed in reactions that produce gases or anhydrides from acids.

Chemical Reactions

Chemical reactions involve substances known as reactants transforming into new substances called products. This transformation takes place through the breaking of old bonds and formation of new ones. When sulfuric acid is involved, it frequently acts as a stimulant, promoting the release of water, thereby aiding in the chemical conversion process.

• Reactions can be endothermic or exothermic, meaning they can either absorb or release heat.
• During reactions involving sulfuric acid, dehydrating effects are common.

For instance, when sulfuric acid is added to formic acid (HCOOH), it initiates a reaction process leading to the production of carbon monoxide (CO) and water (H₂O). The role of sulfuric acid is pivotal as it not only facilitates but sometimes drives the entire chemical reaction forward by its nature.

Balanced Equations

In chemistry, a balanced equation is crucial because it ensures that the same amount of each atom is present on both sides of the equation. This reflects the law of conservation of mass, which states that matter cannot be created or destroyed in a closed system.

• To balance an equation, count the number of atoms for each element on both sides until they match.
• Balanced equations are essential for accurate reaction representation and calculations.

Consider the dehydration of phosphoric acid (H₃PO₄) by sulfuric acid, forming metaphosphoric acid (HPO₃) and water. Balancing this reaction assures that the same quantities of hydrogen, phosphorus, and oxygen are accounted for before and after the reaction:\[\text{H}_3\text{PO}_4 \rightarrow \text{HPO}_3 + \text{H}_2\text{O}\].Each element is counted to ensure coherence in the chemical transformation.

Acid Dehydration

Acid dehydration is a process where acids lose hydrogen and oxygen atoms in the form of a water molecule, often facilitated by a dehydrating agent like sulfuric acid. This can lead to the formation of different chemical substances, as compounds are transformed by the removal of water.

• Dehydration commonly results in the formation of gases or anhydrides.
• It is a critical step in industrial synthesis and various laboratory experiments.

When reacting with nitric acid (HNO₃), sulfuric acid helps it decompose, forming nitrogen dioxide (NO₂) and water along with the release of oxygen. This reaction is represented by:\[\text{2 HNO}_3 \rightarrow \text{2 NO}_2 + \text{H}_2\text{O} + \frac{1}{2} \text{O}_2\].The process showcases how sulfuric acid utilizes its dehydration capability to transform and decompose acids into their gaseous components.