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 \( 0.04 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4} \) is \( 0.08 \mathrm{~N} \) (option d).

Step 1: Understand the Concept of Normality

Normality is a measure of concentration equivalent to molarity multiplied by the equivalent factor. For acids, the equivalent factor is based on the number of moles of hydrogen ions produced per mole of acid. Sulfuric acid, \( \mathrm{H}_{2}\mathrm{SO}_{4} \), dissociates in water to produce two hydrogen ions (\( \mathrm{H}^+ \)) per molecule.

Step 2: Calculate the Equivalent Factor

Since \( \mathrm{H}_{2}\mathrm{SO}_{4} \) produces two hydrogen ions per molecule, its equivalent factor is 2.

Step 3: Use the Formula for Normality

Normality (\( N \)) is calculated using the formula \( N = M \times \text{Equivalent Factor} \). Given \( M = 0.04 \mathrm{M} \) and Equivalent Factor = 2, substitute these values into the equation.

Step 4: Perform the Calculation

Substitute the values into the formula: \[ N = 0.04 \text{ M} \times 2 \]. Simplify to find \( \text{Normality} = 0.08 \text{ N} \).

Key Concepts

Molarity

Molarity is a fundamental concept in chemistry that refers to the concentration of a solution. It is defined as the number of moles of solute present per liter of solution. This metric is often used in laboratories and chemistry calculations to measure how concentrated a solution is. For instance, a solution with a molarity of 1 M means it has one mole of solute in every liter of solution. Molarity is expressed with the unit "M" which stands for moles per liter.To calculate molarity, you can use the formula:\[ M = \frac{n}{V} \]where:- \( n \) is the number of moles of the solute.- \( V \) is the volume of the solution in liters.Knowing the molarity is crucial, especially when you need to prepare a solution with a specific concentration. For example, in the given problem, the molarity of sulfuric acid solution was provided as 0.04 M, showing its concentration before any further calculations for normality.

Equivalent Factor

The equivalent factor is an important component when transitioning from molarity to normality. It signifies how many pieces of reactive ions are produced by a molecule in a chemical reaction. Specifically for acids, the equivalent factor is based on the number of hydrogen ions that each molecule can donate.For example, the sulfuric acid molecule, \( \mathrm{H}_{2}\mathrm{SO}_{4} \), dissociates to yield two hydrogen ions (\( \mathrm{H}^+ \)). This indicates its equivalent factor is 2. This means that for every mole of sulfuric acid, there are two moles of hydrogen ions making it an important consideration when calculating normality.Understanding equivalent factors allows chemists to fully interpret the reactivity and concentration strength of a solution in terms of the reactive species it delivers.

Sulfuric Acid

Sulfuric acid, known scientifically as \( \mathrm{H}_{2}\mathrm{SO}_{4} \), is a powerful and widely used acid in various industrial and laboratory processes. It is a strong acid, meaning that it dissociates completely in solution.When dissolved in water, sulfuric acid, due to its composition, releases two hydrogen ions for every molecule of \( \mathrm{H}_{2}\mathrm{SO}_{4} \). This complete dissociation makes it a diprotic acid, emphasizing the role it plays as a prominent acid in reactions producing hydrogen ions.Due to its strong acidic nature, sulfuric acid is extensively used in the manufacturing of chemicals, the processing of minerals, as well as in clean-up processes. It's important for students to recognize its two hydrogen ions' release because this feature significantly affects the calculation for normality and equivalent factors.

Hydrogen Ions

In acid-base chemistry, hydrogen ions are crucial as they define the acidic nature of substances. For any given acid, hydrogen ions (\( \mathrm{H}^{+} \)) are what strip an acid of its proton donor capabilities, making them key players in neutralizing bases and participating in chemical reactions.The concentration of hydrogen ions in a solution determines its pH level. A solution that releases more hydrogen ions will have a lower pH, rendering it more acidic. For sulfuric acid specifically, each molecule dissociates to deliver two hydrogen ions, boosting its capability to react strongly with bases and contributing significantly to the solution's acidity.Recognizing the role of hydrogen ions in dissociation is important for understanding the calculation of normality. It's the factor that multiplies the molarity to achieve the final normality reading, showcasing its participatory power in chemical reactions.