Question

Write the balanced chemical equation for the neutralization reaction between \(\mathrm{H}_{2} \mathrm{SO}_{4}\) and \(\mathrm{Cr}(\mathrm{OH})_{3}\). What is the salt?

Short answer

The balanced equation is \( 3\text{H}_2\text{SO}_4 + 2\text{Cr(OH)}_3 \rightarrow \text{Cr}_2(\text{SO}_4)_3 + 6\text{H}_2\text{O} \); the salt is chromium(III) sulfate \( \text{Cr}_2(\text{SO}_4)_3 \).

Step-by-step solution

Write the Reaction Components

Identify the reactants in the neutralization reaction. The reactants are \( \text{H}_2\text{SO}_4 \) (sulfuric acid) and \( \text{Cr(OH)}_3 \) (chromium(III) hydroxide). These will react to form water and a salt.

Find the Reaction Products

In a neutralization reaction between an acid and a base, water (\( \text{H}_2\text{O} \)) and a salt are produced. For \( \text{H}_2\text{SO}_4 \) and \( \text{Cr(OH)}_3 \), the salt produced is chromium(III) sulfate, \( \text{Cr}_2(\text{SO}_4)_3 \). Write the initial unbalanced equation: \[ \text{H}_2\text{SO}_4 + \text{Cr(OH)}_3 \rightarrow \text{Cr}_2(\text{SO}_4)_3 + \text{H}_2\text{O} \]

Balance the Equation

To balance the chemical equation, ensure that there are equal numbers of each type of atom on both sides of the reaction. Start by balancing the chromium (Cr), followed by sulfate (\( \text{SO}_4^{2-} \)), and finally hydrogen (H) and oxygen (O):1. Balance Cr by placing a coefficient of 2 in front of \( \text{Cr(OH)}_3 \): \[ \text{H}_2\text{SO}_4 + 2\text{Cr(OH)}_3 \rightarrow \text{Cr}_2(\text{SO}_4)_3 + \text{H}_2\text{O} \]2. Balance \( \text{SO}_4^{2-} \) by placing a coefficient of 3 in front of \( \text{H}_2\text{SO}_4 \): \[ 3\text{H}_2\text{SO}_4 + 2\text{Cr(OH)}_3 \rightarrow \text{Cr}_2(\text{SO}_4)_3 + \text{H}_2\text{O} \]3. Balance H and O atoms by ensuring the number of water molecules is 6: \[ 3\text{H}_2\text{SO}_4 + 2\text{Cr(OH)}_3 \rightarrow \text{Cr}_2(\text{SO}_4)_3 + 6\text{H}_2\text{O} \]

Verify the Balancing

Check the final balanced equation to ensure both sides have the same number of each type of atom:- Sulfur: 3 on each side- Chromium: 2 on each side- Oxygen: 18 on each side (from \( \text{Cr(OH)}_3 \), \( \text{SO}_4^{2-} \), and water)- Hydrogen: 12 on each sideThe balanced equation is confirmed to be: \[ 3\text{H}_2\text{SO}_4 + 2\text{Cr(OH)}_3 \rightarrow \text{Cr}_2(\text{SO}_4)_3 + 6\text{H}_2\text{O} \]

Identify the Salt

The salt in the reaction is the product that is neither water nor an acid/base. In this case, the salt formed is chromium(III) sulfate, \( \text{Cr}_2(\text{SO}_4)_3 \).

Key concepts

Neutralization Reaction

A neutralization reaction is a type of chemical reaction in which an acid and a base react to form water and a salt. This is a classic example of a chemical process where the acidity of the acid and the basicity of the base exactly cancel each other out. The primary goal of such reactions is to achieve a neutral pH, where the pH level is around 7. This type of reaction is essential in various scientific and industrial processes.

• Understanding Components: The typical components of a neutralization reaction are an acid and a base. In our example, sulfuric acid (an acid) reacts with chromium(III) hydroxide (a base).
• Result and Significance: The result is the formation of water and a salt, specifically chromium(III) sulfate in this instance. Neutralization reactions are crucial in fields such as chemistry, medicine, and environmental science.

Neutralization reactions are not only academically fascinating, but they also have practical applications, like the treatment of waste to reduce its acidity or alkalinity.

Sulfuric Acid

Sulfuric acid (chemical formula: \(\text{H}_2\text{SO}_4\)) is a highly corrosive strong mineral acid. It is a vital industrial chemical used in various applications and is known for its ability to donate two protons (H+) in chemical reactions, making it diprotic.

• Properties: Sulfuric acid is a colorless oily liquid, soluble in water with an exothermic reaction, and has a very high boiling point.
• Uses: It is used in manufacturing fertilizers, refining oil, and processing metals. It also plays a pivotal role in automotive batteries.
• Reactivity: Sulfuric acid reacts with bases, such as chromium(III) hydroxide, to form salts and water, showcasing its central role in neutralization reactions.

Due to its potent nature, sulfuric acid must be handled with extreme care to avoid severe burns or other injuries.

Chromium(III) Hydroxide

Chromium(III) hydroxide, represented by the formula \(\text{Cr(OH)}_3\), is an inorganic compound that acts as a base in chemical reactions, such as neutralization.

• Properties: It is typically seen as a green solid when isolated. It does not readily dissolve in water, which affects its reactivity in solutions.
• Role as a Base: In reactions, chromium(III) hydroxide can accept protons from acids, like sulfuric acid, leading to the formation of a salt—in this case, chromium(III) sulfate.
• Applications: It is utilized in various ways, including as a pigment known as "Guignet's Green" and in metal finishing processes.

Chromium(III) hydroxide provides an example of a relatively mild base participating actively in a neutralization process.

Chromium(III) Sulfate

Chromium(III) sulfate, \(\text{Cr}_2(\text{SO}_4)_3\), is the salt formed in the neutralization reaction between sulfuric acid and chromium(III) hydroxide.

• Formation: The reaction is defined by the balanced chemical equation: \[3\text{H}_2\text{SO}_4 + 2\text{Cr(OH)}_3 \rightarrow \text{Cr}_2(\text{SO}_4)_3 + 6\text{H}_2\text{O}\] In this equation, chromium(III) sulfate is the salt produced.
• Properties: Chromium(III) sulfate appears as a violet solid and is soluble in water, which makes it useful in aqueous solutions.
• Applications: It is extensively used in tanning processes for leather, offering improved durability and quality of finished leather products.

This compound illustrates how diverse and beneficial salt products can be formed through straightforward chemical reactions.