Properties of Water
Name
Per
 Polarity is the unequal sharing of electrons. This allows it to dissolve other polar substances very easily
as a universal solvent.
 Hydrogen bonds are a weak bond between two molecules resulting from an electrostatic attraction
between a proton in one molecule and an electronegative atom in the other.
 Hydrogen bonding is responsible for the special properties that water has.
 Water has a very high melting and boiling point compared to other similar molecules.
 The structure of water molecules together expand upon freezing. This causes solid water (ice) to float
on top of liquid water. Which works as an insulator for lakes in the winter.
 Special properties of water:
o Cohesion is the attraction of water molecules to other water molecules.
o Adhesion is the attraction of water molecules to other types of molecules.
 NOTE - Adhesion and Cohesion are responsible for capillary action, which is the
movement of water up from the roots of plants to the leaves through the veins.
o Water has a high specific heat. Sometimes this is called heat capacity or specific heat capacity.
This means that water requires a great deal of energy to increase in temperature. The reason it
takes so much energy to raise water’s temperature is because of the hydrogen bonds. This gives
water the ability to moderate temperature in the environment.
o Water is known as the universal solvent. This means that water is able to dissolve many
substances, like salt, oxygen and carbon dioxide.
o The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14.
Answer the following questions in COMPLETE SENTENCES.
1. Why do people need to drink water?
2. Why does our blood need to have a lot of water in it?
3. What would happen to the fish in cold regions if ice didn’t float?
4. Explain how hydrogen bonding affects adhesion and cohesion.
Explain why the special properties of water make it essential for life, including:
5. Polarity
6. Hydrogen bonding
7. Cohesive and adhesive behavior
8. Ability to moderate temperature
9. Universal solvent behavior
10. Expansion upon freezing.
11. How does heat capacity of water affect temperature change?
12. How do cohesion and adhesion affect capillary action?
Vocabulary
Polar
Molecule
Cohesion
Surface
Tension
Adhesion
Capillary
Action
Solution
Solute
Solvent
Suspension
pH scale
Acid
Base
Buffer
Hydrogen
Bonds
Specific Heat
(Capacity)
Definition
Provide an example or draw a picture
Answers
1. Why do people need to drink water?
Your body uses water in all its cells, organs, and tissues to
help regulate its temperature and maintain other bodily functions. Because your body loses waterthrough
breathing, sweating, and digestion, it's important to rehydrate by drinking fluids and eating foods that
contain water.
2. Why does our blood need to have a lot of water in it?
Our cells need to be filled with water to
work properly because the enzymes inside them only work in solution. Water is also the means by which
transport occurs in our bodies' blood is mostly water and has hormones and gasses dissolved in it as well
as toxins such as urea, which are removed from the body with yet more water.
3. What would happen to the fish in cold regions if ice didn’t float?
It is true that some fish can
spend the winter frozen in ice and come out swimming once the ice melts. Not all fish get caught in the
ice, of course. Ponds and lakesfreeze from the top down, meaning that beneath the icy surface there is
usually a layer of liquid water where fish swim.
4. Explain how hydrogen bonding affects adhesion and cohesion.
Cohesion holds hydrogen
bonds together to create surface tension on water. Since water is attracted to other
molecules,adhesive forces pull the water toward other molecules.
Explain why the special properties of water make it essential for life, including:
5. polarity
6. hydrogen bonding
7. cohesive and adhesive behavior
8. ability to moderate temperature
9. universal solvent behavior
10. expansion upon freezing
11. How does heat capacity of water affect temperature change?
Water has a high specific heat
capacity. While this idea sounds a bit intimidating it is actually very simple - all it means is that it takes a lot
of energy to make water a little bit warmer. This is why on a hot day the sand on a beach can be too hot to
walk on but the sea still feels cool; the energy from the sun is enough to heat the sand a lot but the water only
a little. This has some very important implications, especially for organisms that live in water. Seas, lakes
and rivers maintain a much more constant temperature than air, which means that animals can live in water
all year round without having to adapt to large temperature changes (What do you think would happen if
water cooled more easily? What problems might this pose to organisms living in a small pond?). This also
means that our body temperature is reasonably difficult to change quickly and hence makes our brain's job of
maintaining a constant body temperature much easier (What might happen if our body temperature changed
quickly and easily?).
12. How do cohesion and adhesion affect capillary action?
Capillary action occurs when
the adhesion to the walls is stronger than the cohesive forces between the liquid molecules. The
height to which capillary action will take water in a uniform circular tube (picture to left) is limited by surface
tension and, of course, gravity