Water and Aqueous Solutions

1
Water and Aqueous Solutions

• Chapter 17.1 and 17.2

2
Surface Properties

• Waters surface
• acts like skin
• Water has a high surface
• tension

Water Strider can walk on waters surface
tension
3
Surface Properties

• surface tension page 477
• Inward force that tends to minimize the surface
  area of a liquid
• Tends to hold liquid drops in spherical shape

4
More Surface Properties

• All liquids have surface tension
• Waters tension is higher than most others
• Surface tension can be decreased by adding a
  surfactant p 477
• Soap or detergent
• Interfere with hydrogen bonds

5
Specific Heat Capacity pg.478

• The heat, in joules or calories, required to
  raise the temperature of 1 g of a substance 1ºC
• For water 4.18 J
• Water has a high heat capacity

6
Evaporation and Condensationpg. 479

• Heat of vaporization
• Amount of energy needed to change 1 g from liquid
  to gas
• For water 2.26 kJ
• Very high
• Caused by hydrogen bonding
• evaporate energy is absorbed by water from
  surroundings
• condensation energy is given off by water and
  absorbed by surroundings

7
Molecular Compounds

• Molecular compounds of low molar mass have low
  boiling points at atmospheric pressure
• Water is an exception
• Hydrogen bonding is very extensive
• Compounds with high boiling points have hydrogen
  bonds

8
Ice

• As most liquids cool their density increases
• Caused by contraction
• At 4ºC water stops contracting and starts
  expanding
• Density goes down
• Ice floats

9
More Ice

• Open space in ice
• Caused by hydrogen bonds
• Molecules do not have enough kinetic energy when
  cooled to move