PPT on Physical and Chemical Properties of Water will cover the following topics: Physical Properties of Water, Chemical Properties of Water, How water acts as the solvent of life? Solvent properties of water, High heat capacity of water, High heat of vaporization, High heat of fusion, Density and freezing properties, High cohesion, adhesion and surface tension of water, Water acts as a reactant, Phases of Water, Freezing, Melting, Vaporization, Condensation, Sublimation, Deposition, High cohesion, adhesion and surface tension of water, Density and freezing properties, solvent of life, Hydrophilic and Hydrophobic Interactions in Water
Physical and Chemical Properties of Water (PPT)
Unusual Properties of Water (Slides Transcript)
Physical & Chemical Properties of Water
Water: The Solvent of Life
- Water is the most abundant substance in living systems
- Makes up ~70% or more of body weight
- Life originated in water
- Water’s unusual physical and chemical properties make it the “solvent of life”
States of Water
- Water exists in three phases:
- Solid: Ice
- Liquid: Liquid water
- Gas: Water vapor (steam)
- Phase transitions:
- Freezing, Melting, Vaporization, Condensation, Sublimation, Deposition
Unusual Properties of Water
Due to three main factors:
- Small size of water molecules
- Polarity of water molecules
- Formation of hydrogen bonds between molecules
Physio-Chemical Properties Summarized:
- Solvent properties
- High heat capacity
- High heat of vaporization
- High heat of fusion
- Density & freezing properties
- High cohesion, adhesion, and surface tension
- Water as a reactant
(1) Solvent Properties of Water
- Polar solvent dissolves ions, salts, sugars
- Surrounds ions, increasing mobility & reactivity
- Called the “universal solvent”
- Non-polar molecules (lipids, fatty acids) do not dissolve
- Hydrophilic and hydrophobic interactions affect cell structure & function
Biological Significance of Solvent Properties:
- Medium for enzymatic reactions
- Helps form cell membranes, protein/enzyme structure
- Transport medium in blood, lymph, digestive tract, excretory systems, plant transport
(2) High Heat Capacity of Water
- Heat capacity: energy to raise temp of 1kg water by 1°C
- Due to hydrogen bonds
- Minimizes rapid temp fluctuations
- Maintains stable cell environment
(3) High Heat of Vaporization (Boiling Point)
- Energy needed to break intermolecular forces and vaporize water
- High due to hydrogen bonds
- Boiling point: 100°C
- Cools surroundings (e.g., sweating, transpiration)
- Conserves water during heat loss
(4) High Heat of Fusion (Melting Point)
- Energy needed to melt ice
- Melting point: 0°C
- Ice needs high energy to thaw; water must lose much energy to freeze
- Protects cells in cold climates from freezing damage
(5) Density and Freezing Properties
- Ice is less dense than liquid water
- Density decreases below 4°C
- Ice floats due to expansion (~9%)
- Floating ice insulates and supports aquatic life
- Promotes nutrient cycling in water bodies
(6) High Surface Tension and Cohesion
- Cohesion: water molecules stick via hydrogen bonds
- Surface tension: results from cohesive forces
- Causes water to form droplets (spherical shape)
- Drives water transport in plants (transpiration pull)
(7) Water as a Reactant in Cells
- Participates in reactions
- Slight ionization (H⁺ and OH⁻ release)
- Reactant in photosynthesis
- Involved in hydrolysis and condensation reactions (e.g., protein, polysaccharide, lipid synthesis)
References:
- Berg, J.M., Tymoczko, J.L., & Stryer, L. (2012). Biochemistry
- Lehninger, A.L., Nelson, D.L., & Cox, M.M. (2005). Lehninger Principles of Biochemistry
- Voet, D., Voet, J.G., & Pratt, C.W. (2013). Fundamentals of Biochemistry
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