The document discusses the physical and chemical properties of water. It explains that water has a unique relationship between temperature and density, where density increases between 0-4 degrees Celsius before decreasing as temperature continues to drop until freezing. Unlike most substances, ice is less dense than liquid water due to the hydrogen bond formation in its crystalline lattice structure, which causes water molecules to spread out more than in the liquid state. Finally, it notes that an iceberg's larger size below the waterline is because ice is less dense than water.

1. Course: The Water
Unit: The Physical And Chemical Properties of
Water.
Instructor: Asma Alkhozaimi

2. O Density means the mass per unit volume of a
substance, but on Earth you can assume mass is
the same as weight.
O The density, also known as "specific gravity”, so
as long as an object is made up of molecules,
and thus has size, it has a density. Density is just
the weight for a chosen amount (volume) of the
material.

3. O Water is unique in the way temperature affects its
density.
O Most substances increase in density as
temperature decreases because the molecules
making up the substance begin to move more
slowly and get closer together.
O At to 4 degrees C , t he density of water increases
and then its density begins to decrease as the
temperature decreases to 0 degrees C, the
freezing point of water.

5. O In the picture below, the iceberg is below the water
level. Actually, almost all of the volume of an iceberg is
below the water line. This is because the ice's density
being less than liquid water's density. When freezing,
the density of ice decreases by about 9 percent.

6. O At the freezing point, hydrogen bonds relax and
form a crystal lattice that keeps molecules further
apart than they are in liquid water.
O In the Ice, the molecules align themselves in a
regular lattice, while the molecules in the liquid
align more randomly as in the liquid form.
Therefore, the lattice arrangement allows water
molecules to be more spread out than in a liquid,
and, thus, ice is less dense than water.

7. O Howard Perlman, U. (2014). Water
Density (water properties), USGS Water
Science School. [online] Water.usgs.gov.
Available at:
http://water.usgs.gov/edu/density.html
[Accessed 1 Dec. 2014].
O science museum, (2014). Icebergs.
[image] Available at: http://goo.gl/Ozqzew
[Accessed 1 Dec. 2014].