Question

Why is the presence of a dipole moment in the water molecule so important? What are some properties of water that are determined by its polarity?

Short answer

The presence of a dipole moment in the water molecule is vital due to its molecular polarity, resulting from the difference in electronegativity between oxygen and hydrogen atoms. This polarity gives rise to several essential properties, such as hydrogen bonding, high heat capacity, cohesion and adhesion, universal solvent abilities, and high surface tension. These properties play critical roles in temperature regulation, biological processes, and the sustenance of life and the environment.

Step-by-step solution

Understand Dipole Moment and Polarity of Water Molecule

Dipole moment is a measure of the molecular polarity, which is the difference in electronegativity between two atoms in a bond. Water molecule, consisting of two hydrogen atoms and one oxygen atom (H2O), has a molecular geometry that results in a net dipole moment. This happens because oxygen atom is more electronegative than hydrogen atoms, making the oxygen atom partially negative and the hydrogen atoms partially positive. The net result is a polar covalent bond, contributing to the overall polarity of the water molecule.

Properties of Water due to Polarity

The polarity of the water molecule gives rise to several essential properties that determine its unique physical and chemical characteristics. Some of the properties determined by water's polarity are: 1. Hydrogen bonding: Due to the polarity of the water molecule, it can form hydrogen bonds with other water molecules, resulting in a relatively high boiling point and melting point for a molecule of its size. 2. High heat capacity: Water's ability to absorb and store heat is due to the hydrogen bonding between water molecules. This high heat capacity is essential for temperature regulation in living organisms and the environment. 3. Cohesion and adhesion: Polarity gives water its cohesive and adhesive properties, allowing it to stick together and to other surfaces. This property is essential for various biological processes, such as the movement of water in plants. 4. Universal solvent: The polar nature of the water molecule allows it to dissolve a large variety of substances, making it the universal solvent. This property helps in the formation of various solutions essential for life processes, such as nutrients dissolved in the blood. 5. High surface tension: The hydrogen bonds between water molecules give water a high surface tension, allowing it to form into droplets and flow in thin streams. This property is crucial for the movement of water in the environment and living organisms. By understanding the importance of the dipole moment and the polarity of the water molecule, it becomes clear how these characteristics play a crucial role in determining various properties essential to the sustenance of life and the environment.