Physical and Chemical Properties of Water

Introduction 

Water is the foremost resource for the sustainability of life on Earth. It is very necessary to maintain the life and atmosphere on the Earth. According to the report, an average individual consumes 101 gallons of water in a day. Although, water is used in every day-to-day activity, like cooking, bathing, and so forth. There are distinct types of physical and chemical properties of water.

The chemical formula of water is H2O. It is composed of two major elements, hydrogen and oxygen. In this formula, every two hydrogen atoms are linked with one atom of oxygen. 

The equation can be written as:

H2   + O2 → H2O

The balanced equation for the same;

2 H2   + O2 → 2 H2O

The hydrogen and oxygen are integrated with polar covalent bonds. It means the electrons of hydrogen and oxygen unequally share the atom. The scientific name of water is oxidane. Now, let’s understand about the physical properties of water and chemical properties of water. 

Physical States of Water and its Properties

Let’s learn about the physical properties of water. There are ten major physical properties of water. These are:

Appearance 

In appearance, the water is colorless and odorless. Although, in its natural state, water is a tasteless liquid. The medium of liquid is transparent, which means anything can be seen clearly from behind the water. 

Freezing point

Freezing can be described as a temperature when a liquid starts turning into ice. The freezing point of water is 0°C or 32°F. You also noticed this phenomenon in your refrigerators. Also, the refrigerator temperature of 0°C is maintained for freezing the water.

Boiling point 

The boiling point of any liquid can be described as a temperature when it starts evaporating in the environment or say when it starts turning from liquid to gaseous state. The boiling point of water is 100°C. 

Specific Heat Capacity

Specific heat capacity can be described as the amount of heat required for raising the temperature of any substance. The specific heat capacity of water is 4.2 joules per gram at a temperature of 25°C. The specific heat capacity of water is very high because the hydrogen bonding is very extensive between the molecules of water. 

Density of Water

The density of any substance can be described as the ratio of the mass of any substance to its volume. 1 gm/cc is the density of the water. Although, the density of water differs with temperature and is different for various states. In the solid-state, it is density remains 0.9gm/cc

Viscosity of Water 

Viscosity can be described as an amount of resistance used for deformation at the given rate. If explained in other words, it can be defined as the thickness of any substance. The viscosity of water is 0.89 cP (centipoise). 

Surface Tension of Water

The surface tension of any liquid can be described as the capacity of that liquid to get shrunken in the minimum surface area. The surface tension of water is high and equals 72 mN/m at the temperature of 25°C. Due to the water’s high surface tension, any insect cannot walk on it without hindrance. 

Refractive Index of Water

The Refractive index of any substance is the value demonstrating how fast the light can reach the material. At the temperature of 20°C, the refractive index of water is 1.333. 

Dielectric Constant of Water

Dielectric constant of any substance is the value at which the material starts polarizing by an electric field. The dielectric constant of water is very high. It is equal to 78.6. 

Compressibility of Water

The compressibility of any substance describes its functionality at any temperature and pressure. At the temperature of 0°C, the compressibility of water is 5.1×10−10 Pa−1, and as the temperature increases it reaches up to 45°C, compressibility starts decreasing and reaches up to l4.4 ×10−10 Pa−1. 

Chemical Properties of Water 

Self ionization of water takes place as 

H2O ⇄  H+  + OH–    …………. Kw = [H+ ] [OH–]

Let’s learn about the chemical properties of water. There are three major chemical properties of water. These are:

Amphoteric nature 

A substance is amphoteric when it reacts with both acid and base. So, water can react with both acid and base. Equation that shows its acidic behavior: 

H₂O(l) + NH3(aq)  →  NH4(aq) + OH–(aq)

Equation that shows its basic behavior:

H2O(l) + H2S(aq)  →   H3O+ (aq) + HS– (aq)

Redox reactions

Water is the electropositive element that can reduce hydrogen molecules from its atom. Due to the nature of releasing hydrogen, water can perform various redox reactions 

For instance,

2 H2O(l) + 2 Na(s) →  2 NaOH(aq) + H2(g)

Similarly, in photosynthesis, molecules of water are oxidized to O2. 

Hydrolysis reaction

The tendency of getting hydrated is very high in water due to its high dielectric constant.

For instance, 

SiCl4 + 2 H2O → SiO2 + 4 HCl

So, many ionic compounds can be dissolved in the water. Also, covalent compounds can be hydrolyzed in the water.

Conclusion 

Water or H2O is a transparent and colourless chemical substance. Approximately 70.9% of the Earth’s surface is covered with water. It is the primary fluid of the Earth’s hydrosphere, which is indispensable for sustaining life on Earth. It exists in three different states: Solid, Liquid and Gas. We normally use the liquid state of water in our daily lives. The ice is the solid-state of water, and the vaporization while boiling is the Gas state of water. So, here we learned about the physical and chemical properties of water separately.