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Properties of water

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Water is composed of hydrogen and oxygen atoms and its molecules form tetrahedral structures with hydrogen bonds. It has unique physical properties including high heat capacity and heat of vaporization, allowing it to regulate temperatures. Water exists in three phases - liquid, solid ice, and gas vapor - and its density peaks at 4°C, allowing ice to float. Water's polarity allows it to dissolve many substances and hydrate ions, serving as a universal solvent in the human body and worldwide.

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EARTH’S WATER CONTENT 4/5/2015 2
4/5/2015 3 INSIDE HUMAN BODY
Water is the material cause of all things (Thales, 624 – 546 BC) 4/5/2015 4
COMPOSITION Water is composed of hydrogen and oxygen. Two volumes of hydrogen combine with one volume of oxygen 4/5/2015 5
STRUCTURE An atom of oxygen is bound covalently to two atoms of hydrogen. Tetrahedral angle of 104.5° between the two O–H bonds. a) Oxygen atom has two lone electron pairs  Four H bonds b) Hydrogen bonds through its two H atoms to two other water molecules (forming network) 4/5/2015 6
IntermolecularForces Ionic Forces Dipole Forces Hydrogen Bonding 4/5/2015 7 FORCES OF ATTRACTION
HYDROGEN BONDING 4/5/2015 8 What? Requirements Strength
POLARITY  Magnitude of an atom’s partial charge  a measure of its polarity  Electrically polarized,  Dipole moment  6 X 10-30C m  gas phase.  8 X 10-30 C m) in liquid and ice 4/5/2015 9
4/5/2015 10 HAVE YOU EVER WONDERED?
SOLVENT PROPERTIES 4/5/2015 11  Universal solvent- related to polarity  Slight negative and positive charge- Makes compounds to dissociate  Sphere of Hydration Hydrophilic Hydrophobic
4/5/2015 12 HAVE YOU EVER WONDERED?
THERMAL PROPERTIES 4/5/2015 13 Specific Heat • Highest (1 calorie) • Long time to heat and cool Heat of Vaporization • High (586 cal) • Absorbs heat • Evaporation Boiling and Freezing • 100oC (212oF) and freezes at 0oC(32o F) Water density • 4oC (36o F)– Highly dense • Less dense 0oC(32o F) • Ice floats in water
4/5/2015 14 HAVE YOU EVER WONDERED?
STATES: LIQUID, ICE AND VAPOUR 4/5/2015 15 "Phase-diag2" by Matthieumarechal
4/5/2015 16 HAVE YOU EVER WONDERED?
SURFACE PROPERTIES 4/5/2015 17 SurfaceTension Second highest Surface tension Squeezes the liquid into the shape with the smallest possible surface area. Cohesion Creates a high surface tension at the surface of the water. Adhesion Wettability Capillary action
4/5/2015 18 HAVE YOU EVER WONDERED? F Persson & B Halle, JACS 135, 8735–8748 (2013).S Kaieda & B Halle, J Phys Chem B,
4/5/2015 19 WATER AND PROTEINS StructuralStability Proteinbinding Function J Qvist, M Davidovic, D Hamelberg & B Halle, PNAS 105, 6296–6301 (2008). PDB ID code 2BOP
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Properties of water