Why do polar covalent compounds dissolve in water?

Short Answer

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Question: Explain how polar covalent compounds dissolve in water, highlighting the main types of intermolecular forces involved and their role in the dissolution process. Answer: Polar covalent compounds dissolve in water due to the interaction between their dipole moments and the dipole moments of water molecules. This interaction results in the formation of hydrogen bonds, a strong intermolecular force that occurs between molecules containing hydrogen directly bonded to nitrogen, oxygen, or fluorine atoms. During the dissolution process, hydrogen bonds formed between the polar covalent compound and water molecules pull the molecules into the solution and surround them in a process called solvation. These attractive forces overcome the intermolecular forces within both the compound and water molecules, leading to the dissolution of the polar covalent compound in water.

Step by step solution

01

Understand Polar Covalent Compounds

Polar covalent compounds are formed by the unequal sharing of electrons between atoms with different electronegativities. This unequal sharing results in partial positive and partial negative charges on different parts of the molecule, creating a dipole moment. Examples of polar covalent compounds include HCl, NH3, and H2O.
02

Understand Water Molecules

Water (H2O) molecules are also polar covalent compounds due to the difference in electronegativity between hydrogen and oxygen. Oxygen is more electronegative, so it attracts electrons more readily than hydrogen. This creates a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. Consequently, water molecules have a bent shape with an angle of around 104.5 degrees between the hydrogen-oxygen-hydrogen atoms.
03

Understand Intermolecular Forces

There are several types of intermolecular forces, but for this problem, we will focus on a specific type called hydrogen bonding. Hydrogen bonding is a strong dipole-dipole interaction that occurs between molecules containing hydrogen directly bonded to nitrogen, oxygen, or fluorine atoms. These bonds are interactions between a hydrogen atom with a partial positive charge and a nitrogen, oxygen, or fluorine atom with a partial negative charge in another molecule.
04

Explain the Dissolution Process

The dissolution process of polar covalent compounds in water is driven by the interaction between their dipole moments and the dipole moments of water molecules. When a polar covalent compound is mixed with water, the partial positive and negative charges in the compound attract the opposite charges in water molecules, leading to the formation of hydrogen bonds.
05

Explain the Role of Hydrogen Bonds

Hydrogen bonds formed between the polar covalent compound and water molecules pull the molecules into the solution and surround them, a process called solvation. These attractive forces overcome the intermolecular forces between the polar covalent compound's molecules as well as the hydrogen bonds within the water itself. As a result, the polar covalent compounds dissolve in water due to these strong hydrogen bond interactions.

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