Problem 19 - A Complete Resource Book in Chemistry for JEE Main

Question

Normality of \(0.04 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}\) is (a) \(0.02 \mathrm{~N}\) (b) \(0.01 \mathrm{~N}\) (c) \(0.04 \mathrm{~N}\) (d) \(0.08 \mathrm{~N}\)

Step-by-Step Solution

Answer

The normality of 0.04 M H₂SO₄ is 0.08 N (option d).

Step 1: Understand Molarity

Molarity ( M ) of a solution is defined as the number of moles of solute per liter of solution. Here, we have a solution with a molarity of 0.04 M H₂SO₄.

Step 2: Determine the Valency Factor

Sulfuric acid (H₂SO₄) is a diprotic acid, which means it can donate two protons ( H⁺ ) per molecule in a reaction. Thus, the valency factor (n-factor) for H₂SO₄ is 2.

Step 3: Calculate Normality Using Molarity and Valency Factor

Normality ( N ) can be calculated using the formula: Normality = Molarity × Valency Factor. Here, the molarity is 0.04 M and the valency factor is 2. Thus, Normality = 0.04 M × 2 = 0.08 N.

Step 4: Match the Calculation to the Options

The calculated normality is 0.08 N, which matches option (d) from the given choices.

Key Concepts

Molarity

Molarity is a fundamental concept in chemistry, especially when dealing with solutions. It measures the concentration of a solute in a solution and is typically expressed as moles of solute per liter of solution, denoted by the unit mol/L or simply M.
Molarity helps in understanding how much of a substance is present in a given volume, which is crucial for performing various chemical reactions and calculations.

• To calculate molarity, you divide the number of moles of solute by the volume of the solution in liters.
• For example, a 0.04 M solution means there are 0.04 moles of solute per liter of solution.
• This measurement is vital for preparing solutions and determining how they will react with other substances.

Grasping the concept of molarity ensures a strong foundation for understanding chemical reactions and balancing equations.

Valency Factor

The valency factor, also known as the n-factor, is an important concept in stoichiometry. It reflects the number of electrons that an atom can donate or accept during a chemical reaction.
This is crucial for acids, bases, and salts, where it is used to determine the normality of a solution.
In the case of sulfuric acid (H₂SO₄):

• H₂SO₄ is a diprotic acid, meaning it can release two protons (H⁺) per molecule in a solution.
• This gives it a valency factor of 2, since it can donate two hydrogen ions.
• The valency factor aids in calculating normality by indicating how many reactive ions (or equivalents) are present in the compound.

Knowing the valency factor is key for converting molarity to normality.

Sulfuric Acid

Sulfuric acid (H₂SO₄) is a strong, diprotic acid with significant industrial and laboratory applications. In chemistry, it's frequently used as a strong acid to facilitate chemical reactions and titrations due to its ability to fully dissociate in water.
Understanding its properties gives insight into its behavior in different contexts:

• As a diprotic acid, sulfuric acid can donate two protons, leading to a higher reactivity in solutions.
• This property doubles its valency factor compared to monoprotic acids like hydrochloric acid (HCl), which only donate one proton.
• When calculating the normality of a solution involving H₂SO₄, you must account for its ability to release two H⁺ ions, which affects the acidity and the resultant chemical balance.

Learning about sulfuric acid's characteristics enhances your understanding of both basic chemical principles and complex chemical reactions.