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Water and Life… Ch. 2 Water dissolves MANY compounds in the body allowing The Chemistry of Water… • Water is a polar molecule • Oxygen atom has a stronger pull on e…takes on – charge. • Hydrogen atoms are weaker! Take on + charge. Water dissolves MANY compounds in the body allowing for metabolism to occur! Water’s Polarity Results in Hydrogen Bonding… • Hydrogen bonds form BETWEEN water molecules. • Hydrogen bonds are very weak! • They break and reform constantly… Water dissolves MANY compounds in the body allowing Hydrogen Bonding Organizes Water… •H-bonds •4 Bonds Max Why is this not ionic ? Water dissolves MANY compounds in the body allowing Water Contributes to the Fitness of the Environment… • Life most likely evolved in water. • Living cells = 70-95% water • 75% of the earth is water. • Water exists in three states on earth. • Water has cool characteristics because of its polarity! Water dissolves MANY compounds in the body allowing 1. Water is Cohesive… COHESION: The attraction of a substance for molecules of that same substance. Water H-bonds to water! Water dissolves MANY compounds in the body allowing 2. Water is Adhesive… Ad ADHESION: The attraction of one type of molecule to a different type of molecule. Water dissolves MANY compounds in the body allowing Co These Two Properties Allow For Capillary Action to Take Place… CAPILLARY ACTION: the ability of a narrow tube to draw a liquid upwards against the force of gravity.( WordIQ.com) Due to Cohesion and Adhesion Water dissolves MANY compounds in the body allowing 3. Water Has Surface Tension… SURFACE TENSION: The ability of a liquid to resist force at its surface. (wikipedia.com) Water stretch! Accounts for the formation of droplets Water dissolves MANY compounds in the body allowing 4. Water Has a High Specific Heat… SPECIFIC HEAT: The amount of heat needed to raise 1.0 gram of a substance 1oC. So large bodies of water act as heat sinks… Water dissolves MANY compounds in the body allowing Evaporative Cooling… Evaporative cooling … Listen carefully and take notes as we talk about… – – – – KE Temp H-bonds Energy released Water dissolves MANY compounds in the body allowing 5. Ice floats… Ice is less dense than water Due to H-bonds Moderates and insulates… > 4°C 4°C Water dissolves MANY compounds in the body allowing 0°C 6. Water is the Universal Solvent • Solution = Solvent + Solute • Aqueous solution-water dissolves MANY things! • Hydrophilic “hydro” “philo” • Hydrophobic “hydro” “phobos” Water dissolves MANY compounds in the body allowing for metabolism to occur. Hydration Spheres… Water dissolves MANY compounds in the body allowing for metabolism to occur. Water’s Dissociation Accounts For pH… • Dissociation of water: – H2O H+ + OH- (1 x 10-7 molecules at any time!) (1 liter H2O = 3.35 x 1025 molecules) • Acids break up in water, releasing H+ ions. • Bases break up in water, releasing OH – ions. Water dissolves MANY compounds in the body allowing for metabolism to occur. In 2010 we stopped here and did the penny hypothesis lab Water dissolves MANY compounds in the body allowing
