Structure and Properties of Water

 Last Updated : 26 Nov, 2021

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Water is a valuable natural resource. Water is essential for the survival
of all living things. We can’t imagine a world without water. Water is
required by animals and plants to complete their daily metabolic
activities. Water is required by plants to synthesize their food through
the photosynthesis process. We can all go days without food but
cannot imagine going days without water; without water, even plants
dry out and shed their leaves.
Water is a colourless and transparent chemical substance that is the
primary constituent of the earth’s crust’s streams, oceans, and lakes.
It is an important fluid that plays an important role in the survival of
life on Earth.
H2O is the chemical formula for water. It consists of two hydrogen
atoms and one oxygen atom held together by covalent bonds. This
liquid makes up 71% of the earth’s surface.
States of Water
1. Water in its solid state is referred to as ice. Water freezes to form
ice at 0 degrees Celsius (freezing point of water).
2. Water in its liquid state covers the majority of the earth’s surface. It
is used in a wide variety of applications.
3. Water vapour is the gaseous state of water. The water reaches its
boiling point at 100 degrees Celsius and is converted into water
vapour.

Physical Properties of Water

 Chemical formula: H2O is the chemical formula for water, as we all

know. Covalent bonds exist between the hydrogen and oxygen
atoms in the water molecule. A single atom of oxygen forms a
connection with two hydrogen atoms.
 Appearance: In its natural condition, water is a colourless,
odourless, and tasteless liquid.
 Boiling Point: Water has a boiling point of 100 degrees Celsius, as
we all know. However, water’s comparatively high boiling point
violates the periodic table’s tendency. Hydrogen (the next hydride)
has a relatively high boiling point in compared to Hydrogen Telluride
 and Hydrogen Sulphide, both of which have low boiling points. This
is due to the extremely strong hydrogen bonds in the water
molecule. It takes a lot of energy for them to break and start boiling.
 Freezing Point: The same notion applies to water’s freezing point.
Water has a freezing point of 0 degrees Celsius. The fact that water
takes a long time to freeze (or even boil) is critical for our
ecosystem’s and existence.
 Density: One of the remarkable properties of water is that it is
dense in its sold condition. The density of water increases as it cools
up to 4°C. However, after that, water gets less dense. Ice floats in
water because of this.
 Viscosity: Due to very strong intermolecular interactions, water has
a high viscosity.
 Solvency: Water is a highly effective solvent. It’s even referred to
as a Universal Solvent.

Chemical Properties of Water

 Amphoteric nature: Water is amphoteric in nature because it can

act as both an acid and a base. Following two reactions show that

H2O (l) + HCl (aq) ⇌ H3O+ + Cl–

water is amphoteric in nature.

H2O (l) + NH3 (aq) ⇌ NH4+ + OH–

 Redox reactions: Water is reduced to a hydrogen molecule by
electropositive elements. As a result, water is a rich source of
hydrogen. Water is oxidised to O2 during the photosynthesis
process. Water is very useful in redox reactions because it can be
oxidised and reduced.
 Hydrolysis reaction: Because of its dielectric constant, water has
a very strong hydrating tendency. It dissolves a wide range of ionic
compounds. Water can hydrolyze some covalent and ionic
compounds.

Structure of Water

Liquid water
The water molecule is made up of two hydrogen atoms that are joined
together by a single chemical bond to an oxygen atom. The nucleus of
the majority of hydrogen atoms is made up entirely of protons. Water
contains two isotopic forms, deuterium and tritium, in which the atomic
nuclei also contain one and two neutrons, respectively. Deuterium
oxide (D2O), also known as heavy water, is used in chemical research
and as a neutron moderator in some nuclear reactors.
Hydrogen atoms in water molecules are drawn to areas with high
electron density and can form weak bonds, known as hydrogen bonds,
with those areas. This means that the hydrogen atoms in one water
molecule are attracted to the nonbonding electron pairs of an adjacent
water molecule’s oxygen atom. The structure of liquid water is thought
to be made up of aggregates of water molecules that constantly form
and re-form. Other unusual properties of water, such as its high
viscosity and surface tension, are explained by this short-range order.
Structures of ice
Intermolecular interactions in the solid-state (ice) result in a highly
ordered but loose structure in which each oxygen atom is surrounded
by four hydrogen atoms, two of which are covalently bonded to the
oxygen atom and the other two (at greater distances) are hydrogen-
bonded to the oxygen atom’s unshared electron pairs.
Because of its open structure, ice has a lower density than liquid water,
in which the ordered structure is partially broken down and the water
molecules are (on average) closer together. Depending on the
conditions, water can freeze into a variety of structures.
Significance of the structure of liquid water
 Water’s liquid state has a very complex structure, which
undoubtedly involves significant molecule association. Because of
the extensive hydrogen bonding among the molecules in liquid
water, the values for properties like viscosity, surface tension, and
boiling point are much higher than would be expected for a typical
liquid with small molecules. Unlike the condensed states of water
(solid and liquid), which have extensive association among the
water molecules, the gaseous (vapour) phase has relatively
independent water molecules separated by large distances.
 The polarity of the water molecule is important in the dissolution of
ionic compounds during aqueous solution formation. The oceans on
Earth contain vast amounts of dissolved salts, which are valuable
natural resources. Furthermore, the hundreds of chemical reactions
that take place every second to keep organisms alive all take place
in aqueous fluids. Furthermore, the solubility in water of substances
such as sugar and salt allows foods to be flavoured as they cook.
Although the solute’s solubility in water is a highly complex process,
the interaction between the polar water molecules and the solute is
crucial.
 When ionic solid dissolves in water, the anions attract the water
molecules’ positive ends, while the cations attract the negative
ends. This is known as hydration. The hydration of a salt’s ions
causes it to break apart (dissolve) in water. During the dissolving
process, the strong forces that existed between the positive and
negative ions of the solid are replaced by strong water-ion
interactions.

Importance of Water

1. Agriculture is the most important use of water. Irrigation is required

for agriculture, and water is a critical component in the production
of food.
2. Depending on the size of the body, the human body contains 50 to
78 % water. To avoid dehydration, humans should drink 7L of water
per day.
3. It is essential for digestion as well as other biological processes that
occur in living organisms. It is essential for the body’s pH to be
maintained. It also aids in the movement of immune system
antibodies.
4. It aids in the regulation of body temperature. Water provides the
body with the necessary cooling effect.
5. Through perspiration and urination, water flushes harmful toxins
from the body. It keeps wastes from accumulating in living
organisms.
6. It is used to create emulsions and solutions that are used in the
washing process.
7. Domestic water consumption accounts for 15% of total water
consumption. Water is used for drinking, bathing, cooking, and
washing dishes, clothes, fruits, and vegetables, as well as brushing
teeth.
8. It is either used in the creation of the product or to cool the
equipment used in the creation of the product. Industrial water is
used to wash, cool, process, transport, dilute or fabricate a product.
Most water is used in the manufacture of chemicals, paper, and
food.
9. It is used in transportation, manufacturing, hydroelectric power,
body waste removal, tourism, and recreation.
Sample Questions
Question 1: What is the most important use of water?
Answer:
Household water use is the most significant everyday use of water for
the majority of people. Domestic use refers to water used in the home
on a daily basis, such as drinking, cooking meals, bathing, washing
clothes and dishes, flushing toilets, and irrigating lawns and gardens.
Question 2: Does water provide energy?
Answer:
Water contains two types of electricity, as well as a variety of other
substances. Kinetic energy is regarded as the first type of energy. This
is electricity, such as action, that is used during process execution.
Water can flow as a result of kinetic energy, and waves can form.
Question 3: What is the natural source of water?
Answer:
Drinking water is derived from natural sources such as groundwater or
seawater. Groundwater is formed when snow and rain seep through
the ground. Water is collected in open rooms and pores, as well as in
sand and gravel deposits known as aquifers.
Question 4: What is hydrogen bonding?
Answer:
A hydrogen bond is an electrostatic force of attraction between a
hydrogen atom that is covalently bound to a more electronegative
atom or group and another electronegative atom with a single pair of
electrons—the hydrogen bond acceptor.
Question 5: What is intra-molecular hydrogen bonding?
Answer:
Intramolecular hydrogen bonds occur within the confines of a single
molecule. When two functional groups of a molecule can form
hydrogen bonds with each other, this happens.