The boiling point of water is unusually high for a small molecule of its size.By comparison hydrogen sulfide H2S is a gas and both methane CH4 and ethane C2H6 are gases at 25°C.Both carbon dioxide and oxygen are heavier than water but are gases at 25°C.This is because the hydrogen bonds require a lot of energy to break.Each hydrogen bond is weak but collectively they require a lot of energy to break the many bonds.As a result it takes a lot of energy to raise the temperature of a mass of water to the point where it evaporates.
Hydrogen Bonding and Boiling Point of Water
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Specification: OCR Biology A (H020), AS-level, 2.1.2 Biological molecules. Topic: Biological Molecules.
Key terms in this lesson
- hydrogen bond
- A weak intermolecular attraction between a slightly positive hydrogen atom on one molecule and a slightly negative atom, such as oxygen or nitrogen, on another.
More in Biological Molecules
- Ions
- Biological Molecules
- Polymers
- Water
- Density of Water
- Cohesion, Adhesion and Surface Tension
- Specific Heat Capacity of Water
- Water as a Solvent
All 63 lessons in Biological Molecules · All OCR AS-level Biology topics