Materials for food technology students

1. Water and ice physical properties and its structure
G BHARATHI
Assistant Professor
Department of Food and Dairy Technology
Mannar Thirumalai Naicker College
Madurai

2. The Water Molecule
 H2O
 Covalent
bond
 Polarity

3. Polarity of water

4. Dissolving Property of Water

5. States of Water

6. Latent Heat

7. Latent Heat

8. Heat Capacity of Water

9. Viscosity of Water

10. Surface Tension of Water

11. Unique Property of Water

12. Density of Water
Temperat
ure
Salinity

13. Transmission of Light

14. Transmission of Sound
Sound and Locating Objects

15. Organisms Depend on Cohesion
Cohesion is responsible
for the transport of the
water column in plants
Cohesion among water
molecules plays a key
role in the transport of
water against gravity in
plants
Adhesion, clinging of one
substance to another,
contributes too, as water

16. Structure of water and ice

17. Liquid water has a
partially ordered
structure in which
hydrogen bonds are
constantly being
formed and breaking
up.
The strong hydrogen bonds also give water a
high cohesiveness and, consequently,
surface tension. This is evident when small
quantities of water are put onto a non-soluble

18. A schematic of the crystal
structure of hexagonal ice
Each H2O molecule has its
four nearest neighbors
arranged near the vertices of
a regular tetrahedron
(shaded) centered about the
molecule of interest. Near
the melting point the O-O
distance is 0.276 nm, and
the lattice parameters are a
= 0.4523 nm and c = 0.7367
nm.

19.  At ordinary (low) pressures the stable phase is termed ice I.
 There are two closely related variants: hexagonal ice Ih,
whose crystal symmetry is reflected in the shape of
snowflakes, and cubic ice Ic.
 Ice Ih is obtained by freezing water; ice Ic is formed by
depositing vapor at low temperatures ( -130°C).
 Amorphous ice can be obtained by depositing vapor at still
lower temperatures and by compressing ice Ih at liquid
nitrogen temperature.
 In addition to the elemental phases are clathrate hydrates.
These are crystalline compounds composed of a large H2O
cage in which Xe, Ar, or CH4, for instance, is entrapped.
Clathrates are of economic interest because they offer an
abundant source of natural gas.

20.  Ice floats because it is less dense than water.
Water has a density of 1.0 gm/cubic cm.
 The density of ice Ih is 0.931 gm/cubic cm.
 But, why is ice less dense than water if both are
made up of molecules of H2O?
In liquid water each molecule
is hydrogen bonded to
approximately 3.4 other water
molecules. In ice each
molecule is hydrogen bonded
to 4 other molecules.

21. Compare the two structures below. Notice
the empty spaces within the ice structure.
Water
caption
Ice
caption
In ice Ih, each water forms four hydrogen bonds with
O---O distances of 2.76 Angstroms to the nearest
oxygen neighbor. The O-O-O angles are 109
degrees, typical of a tetrahedral coordinated lattice
structure. The density of ice Ih is 0.931 gm/cubic cm.
This compares with a density of 1.00 gm/cubic cm.

22. There are twelve different forms of crystalline ice
that are know. The hexaganol form known as ice Ih
is the only one that is found naturally. The lattice
structure of ice 1h is shown here

23. Thank you