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Properties of Water. The Water Molecule A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen.

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Presentation on theme: "Properties of Water. The Water Molecule A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen."— Presentation transcript:

1 Properties of Water

2 The Water Molecule A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms.

3 The Water Molecule Water Molecule

4 The Water Molecule Hydrogen Bonds Because of their partial positive and negative charges, polar molecules can attract each other.

5 The Water Molecule Cohesion is an attraction between molecules of the same substance. Because of hydrogen bonding, water is extremely cohesive.

6 Copyright Pearson Prentice Hall The Water Molecule Adhesion is an attraction between molecules of different substances.

7 Solutions and Suspensions A mixture is a material composed of two or more elements or compounds that are physically mixed but not chemically combined.

8 Solutions and Suspensions Two types of mixtures can be made with water solutions suspensions

9 Solutions and Suspensions Solutions All the components of a solution are evenly distributed throughout the solution. solute—the substance that is dissolved. solvent—the substance in which the solute dissolves.

10 Copyright Pearson Prentice Hall Solutions and Suspensions When a crystal of table salt is placed in warm water, sodium and chloride ions are attracted to the polar water molecules. Na + Cl - Water

11 Copyright Pearson Prentice Hall Solutions and Suspensions Suspensions Some materials do not dissolve when placed in water but separate into pieces so small that they do not settle out easily.

12 Acids, Bases, and pH A water molecule is neutral, but can react to form hydrogen and hydroxide ions. H 2 O   H + + OH -

13 Acids, Bases, and pH The pH scale Chemists devised a measurement system called the pH scale to indicate the concentration of H + ions in solution. The pH scale ranges from 0 to 14.

14 Acids, Bases, and pH At a pH of 7, the concentration of H + ions and OH - ions is equal. The pH Scale Human blood Milk Sea water Normal rainfall Pure water

15 Acids, Bases, and pH Acids An acid is any compound that forms H + ions in solution.

16 Acids, Bases, and pH Bases A base is a compound that produces hydroxide ions (OH - ions) in solution.

17 Acids, Bases, and pH Buffers The pH of the fluids within most cells in the human body must generally be kept between 6.5 and 7.5. Controlling pH is important for maintaining homeostasis. Neutralization: H+ + OH- = H 2 O

18 2-2

19 A molecule in which the charges are unevenly distributed is called a  polar molecule.  cohesive molecule.  hydrogen molecule.  covalent molecule.

20 2-2 A dissolved substance is called a  solvent.  solution.  solute.  Suspension.

21 2-2 A compound that produces hydroxide ions in solution is called a(an)  base.  buffer.  acid.  salt.

22 2-2 Hydrogen bonds between water molecules result from  adhesion between water molecules.  magnetic attractions between water molecules.  uneven electron distribution in each water molecule.  ionic bonds in the water molecule.

23 2-2 On a pH scale, a value of 2 means that the solution has  equal concentrations of H + and OH - ions.  the same concentration of H + ions as pure water.  higher concentration of H + than in pure water.  lower concentration of H + than in pure water.

24 END OF SECTION


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