Structure and Properties of Water

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

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 ecosystems 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 water is amphoteric in nature.

H₂O (l)  +  HCl (aq)   ⇌   H₃O⁺ +  Cl^– 

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.
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.

Structure and Properties of Water- FAQs

Why is the structure of water important?

The polar structure of water and its ability to form hydrogen bonds are responsible for many of water’s unique properties.

Why is water a liquid at room temperature?

Because of hydrogen bonding, water molecules are attracted to each other. This attraction requires more energy to break than the average kinetic energy of water molecules at room temperature, so water remains a liquid.

Why does water have a high boiling point?

The strong hydrogen bonds between water molecules require a lot of energy to break to transition from liquid to gas, resulting in a high boiling point (100°C).

Why does water have a high specific heat?

It takes a lot of energy to raise the temperature of water because the energy goes into breaking hydrogen bonds between water molecules, not just increasing their motion. This high specific heat capacity helps regulate Earth’s temperature.

Why does ice float in water?

When water freezes, the hydrogen bonds form a rigid, open structure (ice lattice) that is less dense than liquid water. This is why ice floats!

Why is water a universal solvent?

Water’s polar nature allows it to dissolve many ionic and polar covalent compounds. The positive and negative ends of the water molecule can attract ions and polar molecules, breaking them apart and surrounding them in solution.