Problem 42 - A Complete Resource Book in Chemistry for JEE Main

Question

The value of \(\ldots \ldots \ldots\) is less for \(\mathrm{D}_{2} \mathrm{O}\) compared to that of \(\mathrm{H}_{2} \mathrm{O}_{2}\) (a) boiling point (b) latent heat of vaporization ( \(\mathrm{J} \mathrm{g}^{-1}\) ) (c) density \(\left(\mathrm{g} / \mathrm{mL}^{-1}\right)\) at \(20^{\circ} \mathrm{C}\) (d) dielectric constant at \(20^{\circ} \mathrm{C}\)

Step-by-Step Solution

Answer

The value that is less for D2O compared to H2O2 is the dielectric constant.

Step 1: Identify the Compounds

Identify the chemical formulas for the compounds given in the exercise: his problem discusses emical properties of heavy water (euterium oxide, 2O) and hydrogen peroxide (2O2).

Step 2: Understand the Property Being Compared

The exercise asks about which property of 2O is less than that of 2O2. Consider the given options as potential answers.

Step 3: Boiling Point Comparison

The boiling points of substances depend on molecular interactions. euterium oxide (2O) has a higher boiling point than hydrogen peroxide (2O2) due to stronger hydrogen bonding.

Step 4: Latent Heat of Vaporization Comparison

Latent heat of vaporization is the energy required to convert a substance from a liquid to a vapor. 2O has a higher latent heat of vaporization compared with 2O2 because of its stronger intermolecular forces.

Step 5: Density Comparison

The density of a substance is its mass per unit volume. 2O is denser than 2O2. Therefore, 2O2 has a lower density.

Step 6: Dielectric Constant Comparison

The dielectric constant reflects a substance's ability to conduct electric flux. 2O has a lower dielectric constant than 2O2. Water (2O) is known for its high dielectric constant compared to most substances.

Key Concepts

Boiling Point Comparison

Boiling point is a physical property that indicates the temperature at which a substance transitions from a liquid to a gas. This property is largely influenced by the strength of the intermolecular forces within the substance. Stronger intermolecular forces mean a higher boiling point.

For instance, deuterium oxide ( 2O) has stronger hydrogen bonds compared to hydrogen peroxide ( 2O2). These stronger hydrogen bonds in 2O result in a higher boiling point. This means more energy is required to break these bonds and convert the substance into a gaseous state.

Remember that boiling point values are crucial in determining the volatility of substances. A higher boiling point suggests less volatility, and vice versa.

Latent Heat of Vaporization

The latent heat of vaporization is the heat energy required to change a liquid into a vapor without a temperature change. It reflects the strength of the attractions between the molecules in the liquid state, similar to boiling point comparisons.

Deuterium oxide ( 2O) has a higher latent heat of vaporization compared to hydrogen peroxide ( 2O2), meaning it requires more energy for vaporization. This stems from the stronger intermolecular forces present in 2O, which need additional energy to be overcome during the phase transition.

Understanding this property is essential in fields such as meteorology and engineering when it comes to energy transfer processes.

Density Comparison

Density is defined as the mass per unit volume of a substance and is a key factor in many scientific calculations. It can influence how substances interact with each other in different environments.

When comparing deuterium oxide ( 2O) and hydrogen peroxide ( 2O2), 2O is found to be denser. This is because the molecules of 2O are heavier and closer packed than those in 2O2. Thus, hydrogen peroxide has a lower density due to its lighter nature.

Understanding density is helpful in predicting how substances will behave when mixed and in various chemical reactions.

Dielectric Constant

The dielectric constant is a measure of a substance's ability to conduct electric flux. It basically determines how well a material can store and transmit electrical energy. Higher dielectric constants indicate better ability to conduct electricity.

In the case of our comparison, deuterium oxide ( 2O) actually has a lower dielectric constant than hydrogen peroxide ( 2O2), despite water generally having a high dielectric constant. This means hydrogen peroxide can conduct electrical flux better in this context.

Dielectric constant is crucial in the design and operation of electronic devices, as well as in the understanding of solvent-solute interactions in chemistry.