Polystyrene polarity of water level

Gas Phase (Water Vapor)

The gaseous phase of water is known as water vapor (or steam) and is characterized by a transparent cloud. Water also exists in a rare fourth state called supercritical fluid, which occurs only in extremely uninhabitable conditions. When water achieves a specific critical temperature and a specific critical pressure (647 K and 22.064 MPa), the liquid and gas phases merge into one homogeneous fluid phase that shares properties of both gas and liquid.

3.13 Phase Diagram of Water

Water freezes to form ice, ice thaws to form liquid water, and both water and ice can transform into the vapor state. Phase diagrams help describe how wate changes states depending on the pressure and temperature.

3.14 Phase diagram of water

The three phases of water – liquid, solid, and vapor – are shown in temperature-pressure space.

3.15 Note the following key points on a phase diagram:

1.       The critical point (CP), above which only supercritical fluids exist.

2.       The triple point (TP), a well-defined coordinate where the curves intersect, at which the three states of matter (solid, liquid, gas) exist at equilibrium with each other.

3.       Well-defined boundaries between solid and liquid, solid and gas, and liquid and gas. During the phase transition between two phases (i.e, along these boundaries), the phases are in equilibrium with each other.

3.16 The Polarity of Water

The polar nature of water is a particularly important feature that contributes to the uniqueness of this substance. The water molecule forms an angle with an oxygen atom at the vertex and hydrogen atoms at the tips. Because 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 (meaning "two poles"). The oxygen end is partially negative, and the hydrogen end is partially positive; because of this, the direction of the dipole moment points from the oxygen toward the center position between the two hydrogens. This charge difference causes water molecules to be attracted to each other (the relatively positive areas are attracted to the relatively negative areas), as well as to other polar molecules. This attraction contributes to hydrogen bonding and explains many of water's properties (including its ability to act as a solvent to many substances).

3.17 Polarity of the water molecule

Owing to the electro negativity difference between hydrogen (H) and oxygen (O) atoms, and the bent shape of the H₂O molecule, a net dipole moment exists. The figure indicates the partial charges that the atoms possess.

A water molecule can form a maximum of four hydrogen bonds by accepting two hydrogen atoms and donating two hydrogen atoms. Although hydrogen bonding is a relatively weak attraction compared to the covalent bonds within the water molecule itself (intermolecular bonds), it is responsible for a number of water's physical properties. One such property is its relatively high melting and boiling points; more energy is required to break the hydrogen bonds between molecules in order to change to a higher energy phase.

3.18 THE PROPERTIES OF RIVER SAND   

The sample of water were taken at random from the sand heaps collected by the contractors for constructional purpose, and may be regarded as fairly representative.