1. Colour Latent heat Density Next Surface Tension Cohesion State at room
temp.
Specific
heat
capacity
Density
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2. Match the property of water with the corresponding significance for life and correctly fill in the table
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3. Property of water Significance for life Answers
Ice is less dense than water
High surface tension
Strong cohesive properties and high tensile strength
Colourless with a high transmission
Liquid at room temperature
In order to evaporate it must absorb a large amount of energy (high latent heat of vaporisation)
Water can absorb a lot of energy for only a small rise in temperature (high specific heat capacity)
Significance for life
The high surface tension of water means that it can form a habitat on the surface of the water
Can be used for cooling organisms by evaporation of for example sweat
Ice forms an insulating layer over water
Conditions are stable in cells and aquatic environments
Can be used for transport and a medium for reactions
Light can pass through cells for photosynthesis
Water can be pulled through plants in a column as the water molecules are held together by H-bonds

4. Property of water Significance for life Next
Ice is less dense than water
High surface tension
Strong cohesive properties and high tensile strength
Colourless with a high transmission
Liquid at room temperature
In order to evaporate it must absorb a large amount of energy (high latent heat of vaporisation)
Water can absorb a lot of energy for only a small rise in temperature (high specific heat capacity)
Significance for life
Ice forms an insulating layer over water
The high surface tension of water means that it can form a habitat on the surface of the water
Water can be pulled through plants in a column as the water molecules are held together by H-bonds
Light can pass through cells for photosynthesis
Can be used for transport and a medium for reactions
Can be used for cooling organisms by evaporation of for example sweat
Conditions are stable in cells and aquatic environments
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5. Surface Tension The surface of water can behave like an elastic sheet
The molecules in the bulk of the liquid are effected by various intermolecular forces of attraction
Those molecules in the surface are not effected by molecules above them, and therefore ‘pull’ together more strongly, effectively resembling a stretched membrane
A habitat can therefore survive on the surface of the water
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6. Colour – transmission of light
Water is colourless and is therefore transparent to light
This means that sunlight can reach the cells and pass through them so that photosynthesis may occur
Reflected by leaves
53%
10%
13%
Sun light 9%
Light absorbed by leaves (typical values):
Near IR 15%
Red 82%
Green 80%
Blue 84% 8%
32% 7% 7%
Transmitted through leaves
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7. Cohesion
Water molecules show a strong attraction to one another, this is called cohesion.
Droplets of water form spheres due to cohesion between water molecules
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8. Latent heat
While changing state, a substance will take in heat energy (solid  liquid  gas), or expel heat energy (gas  liquid  solid) without a change in temperature. This is termed Latent Heat.
temperature
evaporate
GAS
condense
Water has a large latent heat of vaporisation, and therefore absorbs a large amount of heat energy while changing from water to vapour.
LIQUID
melt
solidify
SOLID
time
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9. State at room temperature
Water is a liquid at room temperature. However, all other similar molecules are gases.
Hydrogen bonds form because of polar covalent bonding between the oxygen and hydrogen atoms H O +
2- H O +
2- H O +
2-
Hydrogen bonds act between the water molecules, and they attract them enough so that it behaves as a liquid. H O +
2-
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10. Specific Heat Capacity
The heat needed to raise the temperature of 1kg of water by 1°C is termed the Specific Heat Capacity.
thermometer
Water has a large specific heat capacity, and therefore can absorb large amounts of heat energy before its temperature raises a significant amount.
1kg of water
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11. Density of water Unlike other substances, water expands as it freezes.
Water molecules in ice form a rigid structure so that there is more space between them, this is seen as expansion as a whole H O
Ice
Water H O H O H O H O
Water molecules are able to approach one another quite closely
As water expands when it freezes, its density (mass per unit volume) will decrease.
This means that ice is less dense than water, and will therefore float on top of it.
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