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MODERN BIOLOGY

MODERN BIOLOGY. Ch. 2.14-2.15 Water, Solution, pH. Solution. Mixture in which one or more substances are uniformly distributed in another substance. Solution. Solute into solvent makes a solution . Solute – the substance dissolved in the solution

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MODERN BIOLOGY

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  1. MODERN BIOLOGY Ch. 2.14-2.15 Water, Solution, pH

  2. Solution • Mixture in which one or more substances are uniformly distributed in another substance

  3. Solution • Solute into solvent makes a solution. • Solute – the substance dissolved in the solution • Solvent – the substance in which the solute is dissolved • (Solvent: whichever is in greater quantity)

  4. Solutions • Concentration: the amount of solute in a volume of solvent. • 2g salt diluted up to 100 ml with water = 2% salt solution • Saturatedsolution: no more solute can dissolve. • Aqueous solutions: water is the solvent

  5. Water Dissociation • The breaking apart of the water molecule into two ions of opposite charge. • OH– :Hydroxide • H3O+:Hydronium

  6. In covalent bonds where the “sharing” is unequal (like in water).Because of this uneven pattern of charge, water is a polar compound. POLARITY

  7. Solubility of Water: • Water is very effective in dissolving many other substances • Water dissolves other polar substances including sugars, some proteins, and salt (NaCl) • “Like dissolves like.”

  8. Hydrogen Bonding • The type of attraction that holds two water molecules together is called hydrogen bonding – weak bond – easily broken.

  9. Hydrogen Bonds • Hydrogen bonds in water exert a significant attractive force, causing water to cling to itself and to other substances.

  10. Hydrogen Bonds • Together, adhesion and cohesion enable water molecules to move upward through narrow tubes against the flow of gravity.

  11. Hydrogen Bonds • In organisms, waters ability to absorb large amounts of energy help keep cells at an even temperature despite temperature changes in the environment.

  12. 2.15 Acid & Bases

  13. Acids • Taste sour • A substance that produces H+ ions (protons) when it is dissolved in water. • Strong acids: • strong electrolytes • A substance that completely dissociates (ionizes) in water • when the number of hydronium ions in a solution is greater than the number of hydroxide ions.

  14. Bases • Taste bitter & feel slippery • A substance that produces hydroxide ions (OH-) in water. • Strong bases: • strong electrolytes that contain OH- ions • Metal hydroxide compound that is very soluble in water • when a solution contains more hydroxide ions than hydronium ions.

  15. Acids and Bases • pH: range is 0 to 14. • Near zero is very acidic • Near 14 is very alkaline or basic. • 7 is neutral (an equal # of H+and H3O+ )

  16. Buffers • Substances that minimize changes in pH • Accept H+ ions when it is in excess and donates H+ ions when there aren’t enough

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