Chemistry of the Kitchen:   Water

IV.  Water

A.  The Water Molecule

1.  Structure of the Water Molecule

a.  molecular formula:            structural formula:

b.  Why is water bent?

 

2.  Polarity of the Water Molecule

a.  compare electronegativities of O and H

i.  O has two partial _______ charges

ii.  H has a partial _______ charge

b.  more info

i.  Why is oxygen negative?

ii. How much water is in living things?

B.  Hydrogen Bonding

1.  Hydrogen bonding of water

2.  Cohesion of water

a.  H-bonds form between which atoms in water?

b.  Water can form up to ___________ H-bonds.

c.  The attraction between water molecules is called ______________, and it results from hydrogen bonding.

d.  Why can water form four hydrogen bonds?

 

3.  Dynamics of Hydrogen bonding

 

C.  Properties of Water

1.  Organizing Effects of Water

a.  How do molecules behave in water?

i.  nonpolar

 

ii.  polar

 

iii.  amphipathic

 

b.  Why don't oil and water mix?

c.  Do molecules break apart when they dissolve?

d.  Does water repel nonpolar molecules?

e.  Does water treat all polar molecules alike?

2.  Chemical Reaction with Water

3.  Tensile Strength of Water

a.  tensile strength:

b.  cohesion

c.  adhesion

d.  Why do paper towels sop up water?

4.  Surface Tension of Water

a.  surface tension is a result of:

b. Why don't all small objects float on water?

c.  demo:  overfilling a dish

d.  Other molecules disrupt the surface tension of the water.

i.  What happens to the water in the dish when the surface tension is disrupted?

ii.  What was used to disrupt the surface tension of the water?

iii. How do detergents make water wetter?

5.  High Specific Heat of Water

a.  water can gain or lose heat with little change in temperature because:

b.  How does water's specific heat affect organisms?

c.  What is kinetic energy?

d.  Why do hydrogen bonds cause high specific heat?

6.  Cooling by Evaporation

7.  Boiling

a.  What happens to H-bonds during boiling?

b.  The bubbles in boiling water are.....

c.  The temperature stays the same in boiling water because:

8.  Why Ice Floats

a.  How does the density of ice compare to the density of liquid water?

b.  arrangement of molecules in ice:

c.  arrangement of molecules in water:

d.  How does the density of ice affect life?

9.  Freezing

a.  What happens to the water molecules as they freeze?

b.  What is a lattice?

c.  Can ice evaporate?

D.  Solutions

1.  definitions

a.  solution

b.  solute

c.  solvent

d.  aqueous solution

e.  concentration

2.  solubility

a.  Polarity determines solubility.  Rule of solubility:

b. Three types of molecules

i. 

ii.

iii.

c.  quantitate solubility

i. How does polarity affect solubility?

1). hydrophilic solutes

2).  hydrophobic solutes

3)  amphipathic solutes

ii. How does temperature affect solubility?

iii.  How does the pressure affect solubility?

iv.  How can you wash oil off your hands with water if the two substances are immiscible?

d.  Separations based on solubility

i.  separate salt from sand ....How?

ii.  extractions

1) definition

2) making coffee

a). surface area?

b). hot or cold water?

c).  time of brew?

iii.  chromatography  

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