High School

What special kind of molecular structure does water have? List three unique characteristics of water and explain how each characteristic is related to water's special structure.

A. Molecular structure: Linear; Characteristics: High heat capacity, low surface tension, high boiling point.

B. Molecular structure: Tetrahedral; Characteristics: High heat of vaporization, low heat of fusion, solvent properties.

C. Molecular structure: Bent; Characteristics: High cohesion, low adhesion, high heat of fusion.

D. Molecular structure: Hexagonal; Characteristics: Low heat capacity, high surface tension, low boiling point.

Answer :

Final answer:

b. Molecular structure: Tetrahedral; Characteristics: High heat of vaporization, low heat of fusion, solvent properties.

Water has a bent molecular structure, creating a polar molecule that leads to it having a high heat capacity, a high heat of vaporization, and effective solvent properties, all due to strong hydrogen bonds between water molecules.

Explanation:

The special kind of molecular structure that water has is bent or angular, not linear, tetrahedral, or hexagonal. This structure is a result of two hydrogen atoms covalently bonded to one oxygen atom with an angle between them, creating a polar molecule. This structure leads to some unique characteristics of water:

  • High heat capacity: Water can absorb a lot of heat before it starts to get hot due to the strong hydrogen bonds between water molecules that require a lot of energy to break.
  • High heat of vaporization: The strong hydrogen bonds also mean that a lot of energy is required to convert water from a liquid into a vapor, which helps moderate the Earth's climate.
  • Solvent properties: Water's polarity allows it to be very effective at dissolving other polar and ionic substances, making it known as the 'universal solvent'.

The high surface tension, capillary action, and ability to exist as a liquid at temperatures and pressures where similar sized molecules would be a gas, are additional unique properties that also result from water's bent molecular structure and hydrogen bonding.