Chemical Bonds Quiz: Covalent vs Hydrogen Bonds

Properties of Water

• Covalent bonds are stronger than hydrogen bonds, and the atoms involved in hydrogen bonding are farther apart than in covalent bonds.
• Water is a liquid at standard temperature and pressure (STP) with a temperature of 25 °C and a pressure of 1 atm.
• Water has a high boiling point of 100 °C (212 °F), but this property varies with liquids having the same molecular structure, such as hydrogen sulfide (H2S), which has a much lower boiling point.
• When water freezes, it expands, unlike most liquids, which contract when they solidify.

Unique Characteristics of Water

• Water is an excellent solvent, facilitating the transport of nutrients and waste products, making biological processes possible in an aqueous medium.
• Water has the highest dielectric constant of any common liquid, allowing for high solubility of ionic substances and their ionization in solution.
• Water has a higher surface tension than any other liquid, governing drop and surface phenomena.
• Water is transparent to visible and longer-wavelength fractions of ultraviolet light, allowing light required for photosynthesis to reach considerable depths in bodies of water.
• Water has a maximum density as a liquid at 4 °C, causing ice to float, and restricting vertical circulation in stratified bodies of water.

Heat Properties of Water

• Water has a higher heat of evaporation than any other material, determining the transfer of heat and water molecules between the atmosphere and bodies of water.
• Water has a higher latent heat of fusion than any other liquid except ammonia, stabilizing temperatures at the freezing point of water.
• Water has a higher heat capacity than any other liquid except ammonia, stabilizing temperatures of organisms and geographical regions.

Classification of Water by Source

• Potable water is safe for drinking, cooking, bathing, and washing dishes.
• Non-potable water is contaminated with pollutants, including particulates, toxic metals, or bacteria, and is not drinkable, but has uses like washing sidewalks or irrigation.
• Surface water is found in lakes, rivers, and streams, and is the most convenient source for human activities.
• Groundwater is less convenient to access and is found in underground reservoirs (aquifers), pumped from wells drilled deep into these reservoirs.

Hydrological Cycle

• The hydrological cycle includes all water present on and in the earth, including salt and freshwater, surface and groundwater, water in the clouds, and trapped water in rocks far below the earth's surface.
• The hydrological cycle describes the movement and conservation of water on Earth, involving two distinct processes:
  • Evaporation: the conversion of liquid water from lakes, streams, and other bodies of water to water vapor.
  • Transpiration: the process by which water is emitted from plants through stomata, small openings on the underside of leaves connected to vascular tissue.