copyright cmassengale The Chemistry of Life Properties of Water copyright cmassengale

copyright cmassengale The Water Molecule Neutral Charge – ZERO Have no charge Have an Equal number of p+ and e- Charges aren’t evenly distributed copyright cmassengale

copyright cmassengale The Water Molecule Polarity A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms. (-) (+) copyright cmassengale

copyright cmassengale Hydrogen Bonds Polar water molecules act like magnets and attract each other Hydrogen Bonds The attraction of the Hydrogen end (+) of one molecule for the Oxygen end (-) of another water molecule. They are strong bonds that form between molecules (CO2, H2O, …) copyright cmassengale

copyright cmassengale Hydrogen Bonds copyright cmassengale

copyright cmassengale Cohesion The attraction between molecules of the same substance (e.g. water). H2O attracting other H2O molecules Allows some insects and spiders to walk on water. copyright cmassengale

Adhesion & Capillarity Adhesion - Attraction between H2O molecules and different molecules Cohesion & adhesion produce Capillarity (upward movement against gravity of water through small tubes) Question: How do plants make use of Capillarity? copyright cmassengale

Solutions & Suspensions Water is usually part of a mixture. Because so many things dissolve in water, it is called the Universal Solvent There are two types of mixtures: Solutions Suspensions copyright cmassengale

Properties of Solutions Ionic compounds disperse as ions in water (+ions & -ions spread out among polar water molecules) Solutions are Evenly distributed mixtures SOLUTE Substance that is being dissolved SOLVENT Dissolving Substance for the solute copyright cmassengale

copyright cmassengale Ionic Solutions Na+ ions will be attracted to WHAT END of the water molecule? copyright cmassengale

copyright cmassengale Suspensions Substances that don’t dissolve but separate into tiny pieces. Water keeps the pieces suspended so they don’t settle out. Blood & Cytoplasm are suspensions copyright cmassengale

copyright cmassengale Acids, Bases & pH 1 water molecule in 550 million naturally dissociates into a Hydrogen Ion and a Hydroxide Ion Hydrogen Ion Hydroxide Ion Acid Base H2O  H+ + OH- copyright cmassengale

How much stronger is a pH3 than a pH of 5? The pH Scale Indicates the concentration of H+ ions Ranges from 0 – 14 pH of 7 is neutral pH 0 up to 7  acid … H+ pH above 7 to 14  base… OH- Each pH unit represents a factor of 10X change in concentration How much stronger is a pH3 than a pH of 5? copyright cmassengale

copyright cmassengale Acids Strong Acid = pH 1-3 High in H+ ions Lower number of OH- ions copyright cmassengale

copyright cmassengale Bases Strong Base = pH 11 – 14 High in OH-ions Lower in number of H+ ions copyright cmassengale

copyright cmassengale Buffers Weak acids or bases that react with strong acids or bases Made by the body Prevent sharp, sudden changes in pH (keep pH neutral) Weak Acid Weak Base copyright cmassengale

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