Water the most precious liquid resource available though in abundance in the saline form in oceans and seas is of little use to mankind.
Fresh water resources limited to our river network and rainwater needs to be used prudently to meet the various needs of mankind.
Many substances dissolve in water since it is considered to be a universal solvent, Because of this, water in nature and in use is rarely pure and some of its properties may vary slightly from those of the pure substance.
Like many substances, it can take numerous forms that are broadly categorized by PHASES or say different types of Water forms.
(The liquid phase is the most common known as"water." The solid phase of water is known as ice and commonly takes the structure of hard,amalgamated crystals, such as ice cubes, or loosely accumulated granular crystals, like snow. The gaseous phase of water is known as water vapor (or steam), and is characterized by water assuming the configuration of a transparent cloud. The fourth state of water, that of a supercritical fluid, is much less common than the other three and only rarely occurs in nature. When water achieves a specific critical temperature and a specific critical pressure ( 647 K and 22.064 MPa ), liquid and gas phase merge to one homogenous fluid phase, with properties of both gas and liquid. it almost never occurs naturally. One example of naturally occurring supercritical water is in the hottest parts of deep water hydrothermal vents, in which water is heated to the critical temperature by scalding volcanic plumes and achieves the critical pressure because of the crushing weight of the ocean at the extreme depths at which the vents are located.
An important feature of water is its polar nature. The water molecule forms an angle, with hydrogen atoms at the tips and oxygen at the vertex. Since oxygen has a higher
electro negativity than hydrogen, the side of the molecule with the oxygen atom has a partial negative charge. An object with such a charge difference is called a dipole. The charge differences cause water molecules to be attracted to each other (the relatively positive areas being attracted to the relatively negative areas) and to other polar molecules
Water is relatively transparent to visible light, near ultraviolet light, and far-red light, but it absorbs most ultraviolet light, infrared light, and microwaves. Most photoreceptors and photosynthetic pigments utilize the portion of the light spectrum that is transmitted well through water.
Water sticks to itself (cohesion) because it is polar. Water also has high adhesion properties because of its polar nature. (adhesive forces) are stronger than the cohesive forces. In biological cells and organelles, water is in contact with membrane and protein surfaces that are hydrophilic; that is, surfaces that have a strong attraction to water.
Water has a high surface tension of 72.8 mN/m at room temperature This can be seen when small quantities of
water are placed onto a sorption-free (non-adsorbent and non-absorbent) surface, such as polyethylene or
Teflon, and the water stays together as drops, air trapped in surface disturbances forms bubbles, Due to an interplay of the forces of adhesion and surface tension, water exhibits capillary action whereby water rises into a narrow tube against the force of gravity. Chemically, water is amphoteric: it can act as either an acid or a base in chemical reactions,
When reacting with a stronger acid, water acts as a base; when reacting with a stronger base, it acts
as an acid.
Pure water has the concentration of hydroxide ions (OH−) equal to that of the hydronium (H3O+) or hydrogen (H+) ions, which gives pH of 7 at 298 K. In practice, pure water is very difficult to produce. As cloud droplets form in the atmosphere and as raindrops fall through the air minor amounts of CO2 are absorbed and thus most rain is slightly acidic. If high amounts of nitrogen and sulfur oxides are present in the air, they too will dissolve into the cloud and rain drops producing acid rain. Several isotopes of both hydrogen and oxygen exist, giving rise to several known isotopologues of water. Hydrogen occurs naturally in three isotopes. A second, stable isotope, deuterium (chemical symbol D or ²H), has an additional neutron. Deuterium oxide, D2O, is also known as heavy water because of its higher density. It is used in nuclear reactors as a neutron moderator. The third isotope, tritium, has 1 proton and 2 neutrons, and is radioactive, decaying with a half-life of 4500 days. T2O exists in nature only in minute quantities, being produced primarily via cosmic ray-induced nuclear reactions in the atmosphere. Water with one deuterium atom HDO occurs naturally in ordinary water
The most notable physical differences between H2O and D2O, other than the simple difference in specific mass, involve properties that are affected by hydrogen bonding, such as freezing and boiling, and other kinetic effects. The difference in boiling points allows the isotopologues to be separated.
Consumption of pure isolated D2O may affect biochemical processes - ingestion of large amounts impairs kidney and central nervous system function. Small quantities can be consumed without any ill-effects, and even very large amounts of heavy water must be consumed for any toxicity to become apparent.