Year 11 Chemistry:~ Unit 2: Environmental Chemistry
Chapter 10: Water Essential to Life
10.1 A molecule essential for Life
Water is the most abundant liquid on Earth, covering over ___% of our planet. The
position of Earth in the solar system means that it gains maximum benefits. Out of all
the water available at the Earth’s surface there is only a tiny fraction available to living
things. There has been no detection of liquid water on any planets within our solar
system.
10.2 The water cycle
The water on Earth exists in ________ , ________ and _________ states and readily
changes from one state into another.
*Draw a simplified diagram of Figure 10.4
Water and living things
Water is involved in the reactions of life: ________________ , ______________ .
Photosynthesis: occurs in plant cells, during daylight hours
Respiration: Cells of all oxygen-using life forms use ___________ as their energy
source.
Water has many other functions in plants and animals:
 Water transports nutrients are soluble wastes around the body. The ability of
water to act as a solvent and dissolve a wide range of materials is central to its
functions in the transporting materials in living things.
 Water transfers heat energy from the cell, where it is produced in respiration, to
our body’s surface, where it is lost to the surroundings. Water has the capacity to
store a large amount of heat energy.
 Water also provides your body with a cooling system. Your skin is always moist.
The evaporation of water from a surface is the major cooling mechanism available to
all living things.
Water and climate
The evaporation stage produces water free of dissolved substances (pure water). As well
as transporting water the water cycle also distributes heat around the planet. Warm
water-laden tropical winds blow towards the _______ where they warm the rest of the
Earth.
Australia is the world’s driest continent and frequently experiences long periods of low
rainfall. Rural Victoria has about half a million hectares of land under irrigation, which
used about the same amount of water as metropolitan Melbourne. There are many water
restrictions in action around Australian.
Question: 1 & 2
10.3 Explaining the Properties of Water
The properties of water are quite unusual. Water is a _____________ molecular
compounds, with the formula _______ . The oxygen-hydrogen bonds are ________,
with the oxygen atom having the larger share of the bonding ___________, due to high
______________ . The forces between water molecules are ____________ bonds.
Relatively high melting and boiling temperatures
 Water is the only substance commonly found in all three states under the conditions
normally found on earth.
 Water exists as a liquid over a temperature range corresponding to that commonly
occurring on the earth.
 The melting and boiling temperatures of water are significantly higher than those of
other molecular substances of similar size.
 It is the relatively strong hydrogen bonding forces between the water molecules that
are responsible for its relatively high melting and boiling temperatures.
*Draw a small section of Figure 10.11
High Latent Heat values
 Latent heat

Latent heat of fusion

Latent heat of vaporisation
When you perspire, the water _____________ by absorbing heat energy from your
skin. This heat energy _______ kJ/mol of water is transferred fro your body to the
evaporating water and you feel cooler.
High heat Capacity
Water has a specific heat capacity of ______ Jg-1 C-1 . This means it will take 4.2
Joules of heat energy to increase the temperature of one gram of water by 1 C. The
higher the specific heat capacity of a substance, the more effective it will store heat
energy.
Heat energy= specific heat capacity (Jg-1C-1) x mass (g) x temperature change (°C)
Heat energy = SHC x mass (g) x ∆T (°C)
*Copy out worked example (pg 193)
Expansion on Freezing
As liquid water is cooled the water molecules move more slowly. On approaching freezing
temperatures the molecules take up the arrangement of a typical ice crystal. The water
molecules in ice are more widely arranged. When ice melts the structure is lost,
molecules move closer.
Questions: 3, 4 & 5