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What are physical and chemical properties of water?
In this article learn about the physical and chemical properties of water. Water which in chemistry is known as $H_2O$ is everywhere and is essential for life forms to exist on the planet Earth.
Let us explore some of the physical and chemical properties of water. Water is a chemical compound made up of two hydrogen atoms and one oxygen atom. The liquid form of this compound is typically referred to as water, whereas ice is used to describe the solid phase and steam is used to describe the gas phase.
What is water?
Water $(H_2O)$ is an inorganic, polar compound that, at room temperature, is a tasteless, odourless, almost colourless liquid with a hint of blue. It’s the most studied chemical substance and is called the “universal solvent”.
It is the most common substance on Earth’s surface and the only one that can be found as a solid, a liquid, and a gas. It is also the universe’s third most abundant chemical (behind molecular hydrogen and carbon monoxide).
What are physical properties of water?
The physical properties of water are the properties of water such as its temperature, appearance, boiling and melting points, and so on. These features do not include the properties of water when it reacts with other chemical substances.
- Boiling point:- Any liquid’s boiling point is defined as the temperature at which it begins to evaporate, or, to put it another way, when it begins to transition from a liquid to a gaseous state. Water has a boiling point of 100 °C.
- Freezing point:- The temperature at which a liquid begins to turn into ice is referred to as freezing. Water has a freezing point of 0°C or 32°F. This phenomenon was also observed in your refrigerators.
- Appearance:- The water appears colourless and odourless. Water, in its natural condition, is a tasteless liquid. Because the liquid medium of water is transparent, anything seen from behind the water may be seen clearly.
- Specific Heat Capacity:- The amount of heat energy needed to raise a substance’s temperature per unit of mass is known as specific heat capacity. At 25 °C, water has a specific heat capacity of 4.2 joules per gram. Water has a very high specific heat capacity due to the extensive hydrogen bonding that exists between its molecules.
- Refractive Index of Water:- The number that shows how fast light got to a material is called its “refractive index.” At 20°C, water has a refractive index of 1.333.
- Solvency:- Water works well as a solvent. In fact, it is referred to as a Universal Solvent. Because of the polarity of a water molecule, it can dissolve almost any substance.
However, it is important to note here that nonpolar substances like oil do not dissolve in water and they remain separated. This happens because of the absence of partial positive and partial negative charges in nonpolar molecules. - Density:- Water has the unusual property of being less dense in its solid state. Water’s density does rise as it cools up to 4°C. But water gets less dense after that point. This is the reason why ice floats in water.
- The viscosity of Water:- Viscosity is defined as a measure of a fluid’s resistance to flow. The viscosity of water is 0.89 cP(centipoise).
What are chemical properties of water?
A substance’s chemical property is its characteristic or behaviour that can be observed during a chemical change or reaction. We have already studied about the physical properties of water let us now look at its chemical properties.
- Amphoteric nature:- Water can act as an acid and a base, which means it can be both a proton donor and acceptor.
Equation showing its acidic behaviour
$H_2O(l)+NH_3(aq)\Leftrightarrow NH_{4}^{+}(aq)+OH^{-}(aq)$
Equation showing its basic behaviour
$H_2O(l)+H_2S(aq)\Leftrightarrow H_3O^{+}(aq)+HS^{-}(aq)$ - Self-ionization:- The self-ionization of water is also known as autoionization of water or autodissociation of water. It is an ionization reaction that happens in pure water or in an aqueous solution. During this reaction, a water molecule $(H_2O)$ loses the nucleus of one of its hydrogen atoms (deprotonates), turning it into a hydroxide ion $(OH^-)$.
- Hydrolysis reaction:- Because of its dielectric constant, water has a very strong hydrating tendency. It dissolves a wide range of ionic compounds. Water can also hydrolyze some covalent and ionic compounds.
- Redox reactions:- Water is reduced to a hydrogen molecule by electropositive elements. As a result, water is an excellent source of hydrogen. Consider the following example:
$2H_2O(l)+2Na(s)\rightarrow 2NaOH(aq)+H_2(g)$
Frequently asked questions
Does water have colour?
When looked at in small amounts, it seems colourless, but when it absorbs sunlight, it gives off a tint of bluish light. The color of the water in bodies of water comes from the plants and other living things in the water.
How many types of water are present in nature?
There are two kinds of water.
- Soft water refers to water without any dissolved salts of metals like calcium, iron, or magnesium.
- High mineral content water is referred to as hard water. When water passes through limestone, chalk, or gypsum deposits, which are primarily composed of calcium and magnesium carbonates, bicarbonates, and sulfates, hard water is formed.
Summary
Water is essential for life, and life can only exist where there is water. The shape of water molecules is twisted and polar, with hydrogen having a partial positive charge and oxygen having a partial negative charge. Depending on the temperature and the kinetic energy of its molecules, water can exist in three different states ie., solid, liquid and gas. At room temperature, water is a clear, tasteless, and odourless liquid. In drinking water, you can often find chlorine, silicates, magnesium, calcium, aluminium, sodium, and small amounts of other ions and compounds.