Water and pH

  1. What does it mean that water is polarized
    Water is H-2-O, meaning that it is held together by Covalent Bonds (sharing electrons). Water is said to be Polar Covalent since there is an unequal sharing of electrons leaving the Hydrogen end partially Positive and the Oxygen end partially Negative. This allows for the attraction of other ions (charged molecules).
  2. The Polar Covalent Bond of H-2-O, has a shared electron that orbits which Atom the Oxygen or Hydrogen
  3. Which Atom of the H-2-O, molecule is highly Electronegative
    Oxygen (because the orbiting electron is around the Oxygen most of the time)
  4. What is a Polar Covalent Bond in H-2-O, and where is the bond located
    • The Electrons which are shared between the Hydrogen and Oxygen are not Shared Equally
    • One end is Partialy Negative and the other end Partialy Positive
    • The Bond is located between (within) the connection of the Oxygen and the two Hydrogens
  5. What are Hydrogen Bonds
    • When one molicule has a Partially Positive charged Hydrogen atom, and it attaches to another molicule that has a Partial Negative Charge.
    • They are also Weaker Bonds
  6. Where are Hydrogen Bond formed
    It forms Between two water molecules (the H+ attaches to the O- of the H-2-0) resulting in polar covalent bonds within newly formed water
  7. What will happen to ionic (atoms with charge at the end), compounds when they are placed in water
    The Water will attach to the ions Negtive and Positive charge and the polar charges of the water will break the ion apart
  8. Will water that contains ions conduct water
    Yes it is referred to as Electrolytic
  9. What are the 5 Unique properties of water
    • 1st water is the Universal Salvent
    • 2nd water Cohesive and Adhesive
    • 3rd water resists Changes in Temperature
    • 4th water Resist change of State to a Gas
    • 5th water becomes less dense when it freezes
  10. Define Water is the Universal Solvent
    • What? Most Substances Dissolve in Water
    • Why? Most substances are either ions (charged Atoms) or Polar Covalent Molecules (Unevenly Sharing of Electrons) and their charges allow them to attract the Polar water molecule
    • So? Chemical reactions occure more efficiently when molecules are dissolved
  11. Water is Cohesive and Adhesive
    • What? Water is attraced to other Water Molecules (cohesive) and attracted to most other Substances (adhesive)
    • Why? Because water is polar, it is attracd to itself, and it is attracted to other substances as long as they have a charge
    • So? An important result is cappilary action. Water, as well as blood and plant sap, is drawn up norrow capillarey tubs, because it is attracted both to itself and to walls of the tube. This helps blood and plant sap to flow through plant and animal vessels
  12. Water resists changes in temperature
    • What? It takes a large amount of energy to change the temperature of water
    • Why? The heating of a substance involves an increase in the movement of the molecules. To speed up water requires the breakdown of hydrogen bonds and therefore requires extra energy
    • So? A body of water such as a pond, lake or ocean changes temperature very slowly, thus, making it easyer for aquatic organiss to maintain homeostasis
  13. Water resist change of state to a gas
    • What? It takes a relatively large amont of energy to convert liquid water to vapor
    • Why? In order for liquid water to go off into air as vapor, Hydrogen Bonds must break, this requires much energy
    • So? When sweat evaporates, it takes a relatively large amount of body heat with it, thus cooling the body. Evaporation of water from the ocean also cools the earth
  14. Water becomes less dense when in freezes
    • What? When water freezes, it weighs less per volume then when it was liquid. This means that ice is Lighter then water
    • Why? When water freezes each water molecule formes relatively Permanent Hydrogen Bonds with 4 other water molecules. This lattice structure forces the water moleule further apart from each other than in liquid water where bonds are constently forming and breaking
    • So? when water freezes, the ice floats. therfore life can continue to exist in ponds under the ice.
  15. What are the two ions that form as a result of the water molecule breaking apart
    • Hydrogen, H+
    • Hydroxide OH-
  16. In Pure water for every Hydrogen ion, how many Hydroxide ions will there be
    the number will be equal
  17. pH is a measure of the concentration of only what two ions in a solution
    • Hydrogen, H+
    • Hydroxide, OH-
  18. What is the pH of Pure Water, and why
    • ph of Pure Water is pH7
    • Because the Hydrogen and Hydroxide consentration is Equal
  19. What pH indicates a neutral pH
  20. Which ion is in greater concentration in an Acidic pH
  21. What ion is in greater concentration is a Basic pH
  22. What type of Bond holds together H-2-O
    Covalent Bond (sharing of electrons)
  23. When compaired to Hydrogen, is Oxygen more or less Electronegative
    More Electronegative therefore Oxygen aquires a partial Positive charge, alowing for a Polar Covalent Bond
  24. Are Hydrogen Bonds week or strong
  25. What is it called when Ionic Molecules separate into ions (eg placing NaCl in H-2-O).
    Dissociate or Ionize into a Na+ and Cl-
  26. A solution that contains ions and conducts electricity is called
    Electrolyte or Electrolyic
  27. What is a Buffer
    A solution which reacts with Hydrogen or Hydroxide ions in order to resist change in pH (becoming too Acidic or Basic)
  28. Solutions with Hydrogen ion concentration greater than 1 x 10-7 is Acidic or Basic
  29. What solution (Acidic or Basic) has a pH which is Gearter than 7 and has a higher concentration of OH than H
  30. Acids or Base are substances which release hydrogen ions and therefore lower the pH
  31. Acids or Bases are substances which take up Hydrogen ions and therefore increase the pH
Card Set
Water and pH
Microbiology Lecture