Water (H2O) may be one of the most prized substances on the planet, despite it covering three-quarters of the Earth's surface. Water brings forth life, making it a necessity to preserve it. Many people waste water as if it never runs out; however, its limited supply has many politicians calling it liquid gold. Human beings cannot live beyond three days without water. It hydrates and allows us to function daily. Therefore, studying water chemistry has become vitally important for the survival of our species. As a result, water chemistry has become a popular subject in the scientific community. Despite decades of research, many scientists have been scrambling to learn more about this remarkable substance.
The Three States of Water
Water's versatile composition makes it worthwhile to study. For instance, water can float in its solidified state known as ice. Water expands as it freezes, subsequently making its solidified state less dense than its liquefied form. In contrast, other liquids shrink when they freeze, which causes their solidified state to sink. If water functioned this way, ice would form at the bottom of lakes, rivers, creeks, and oceans. This would make it difficult to thaw during the spring, ultimately affecting all aquatic life. Unlike other substances, water has a very high boiling point at 100 degrees Celsius at sea level. If water behaved similarly to other liquids, the temperatures and pressures found on the planet would make it impossible for life to thrive. This makes water chemistry imperative to know in-depth.
- The States of Water: Solid, Liquid, Gas
- Chemical of the Week: Water (PDF)
- States of Water
- The Three Forms of Water
- Gases, Liquids, and Solids
The Composition of Water
As previously stated, water behaves differently than most liquids. Any logical conclusion would assert that it has a complicated structure. On the contrary, it has a simple molecular structure. Water consists of one oxygen atom and two hydrogen atoms. Both hydrogen atoms share a covalent bond with the oxygen atom through a pair of electrons. Oxygen has an additional pair of electrons unshared with the hydrogen bond. As a result, there are four pairs of electrons that surround the oxygen atom. One pair is shared covalently with the hydrogen bond, and the other resides on the opposite end of the oxygen atom.
- What is the Composition of Water?
- The Chemistry of Water
- Study and Interpretation of the Chemical Characteristics of Natural Water
- The Chemistry of Water: Structure Means Function
- What Do You Need to Know About Water Chemistry and Why?
The word polarity simply refers to a molecule that has both a positively and negatively charged end, such as a water molecule. Water polarity enables other polar molecules to dissolve, such as sugar and salt. Salt is an ionic compound, which means that it forms ions as it dissolves. The human body is composed of 60 percent water, making it an important substance for survival. Water plays an integral part in biological reactions. This is because most reactants need water to dissolve. As a result, water has become coined the universal solvent. Non-polar and non-ionic compounds that do not dissolve in water are called fat soluble. Insoluble substances contain water easily, such as cell membranes and cell walls.
- How Polarity Makes Water Behave Strangely
- The Polarity of Water Results from Hydrogen Bonding (PDF)
- The Effects of Water's Polarity
- Ionic, Polar and Non-polar Molecules
- McGraw-Hill: The Polarity of Water Video
Hydrogen bonding occurs when a hydrogen atom gets pulled together by another by strong forces. Hydrogen bonding typically occurs when partially positive hydrogen atoms lie between partially negative oxygen or nitrogen atoms. Liquid water is different from other substances in that it has as many hydrogen bonds as it does covalent bonds. The hydrogen bonds in water are covalently attached to the oxygen molecule. Hydrogen bonds in heavy water are stronger.
- Hydrogen Bonding in Water
- Intermolecular Bonding: Hydrogen Bonds
- Overview: The Hydrogen Bond
- A Closer Look At Water: Polarity and Hydrogen Bonds
- Intermolecular Forces: Hydrogen Bonding in Water
Other Unique Water Properties
Water shares other unique properties due to its hydrogen bonds. Ice floats because hydrogen separates water molecules further apart than when in its liquid form. The unique physical water properties include strong surface tension, solvency, and a high heat of vaporization. The hydrogen bonds also cause the hydrophobic effect, or exclusion of non-polar solvents. The common adage of "water and oil do not mix" rings true when referring to the hydrophobic effect. It truly is one of the most magnificent water properties produced by this life-giving substance.
- The Properties of Water
- Lesson 10: The Properties of Water
- Sticky Water: Surface Tension
- Water: High Heat of Vaporization
- The Hydrophobic Effect (PDF)
Written By: Lynn Taylor