Презентация на тему Water and its properties

properties of water as the cohesion, adhesion, capillary water

world's streams, lakes, oceans and rain, and is the

(through sweating and vasoconstriction)
Water helps to hydrate the body:

Our cells are composed of roughly 75% water.

Our blood is composed of roughly 90% water.

and pressure, but it often co-exists on Earth with

snow

fog

dew

clouds

one oxygen and two hydrogen atoms that are connected

Water is:
Composed of two hydrogen atoms and one oxygen atoms
H2O
Polar Molecule has oppositely charged ends

covalent

on bonding electrons:
Oxygen ends slightly negative
Hydrogen end slightly positive
Water

bonds:
slightly positive
charge
Charge hydrogen bond between (+) and (-)

slightly negative
charge

Water in a pure state has a neutral pH. As

a various intermolecular forces that hold solids and liquids

ADHESION
Water is attracted to other substances
Water is adhesive to any substance with which it can form hydrogen bonds.

Thus the forces between molecules in a drop of water are cohesive, while the mutual attraction between water and glass represents adhesion.

of a liquid that allows it to resist an

Surface tension allows insects to float and stride on a water surface.

(and all of the things that are dissolved in

meniscus

is the one of the few substances that is

ice floats on water because
it is less dense

at 100 °C and freezes at 0 °C.

The

dissolve in water
Substances such as salt are pulled

acid or a base is called, amphoteric (ampholyte):
acid
base
ampholyte
All the

this increases significantly with the dissolution of a small

reactivity: water can participate in chemical reactions. Example: involvement

of Group 1 (IA or alkali) react vigorously with cold

ions which are held together by electrostatic forces of

acid: HCl (g) + H2O (aq) = H+ (aq) + Cl-(aq)

base: NaOH (s) + H2O (aq) = Na+ (aq) + OH-(aq)

salt: NaCl(s) + H2O (aq) = Na+ (aq) + Cl-(aq)

The process of splitting of the molecules into ions of an electrolyte is called dissociation .

is cleaved into two parts by the addition of

AB + H-OH ⇌ A-H + B-OH

HYDROLYSIS

its hardness. General hardness (GH) is caused by the

problems. First, the metal cations react with soaps, causing

In boilers, the deposits act as thermal insulation that impedes the flow of heat into the water; this not only reduces heating efficiency, but allows the metal to overheat, which in pressurized systems can lead to catastrophic failure.

(non-carbonate) hardness:
CaCl2, CaSO4
MgCl2, MgSO4
GENERAL HARDNESS:
GH = TH + PH

bi-carbonates of calcium and magnesium. It can be removed

MgCO3 is slightly soluble in water but heating will cause its hydrolysis into the much less soluble Mg(OH)2


So simple boiling and filtering of water remove temporary hardness.

TEMPORARY HARDNESS

and sulphates of calcium and magnesium. These salts do

PERMANENT HARDNESS

Surfactant a substance that tends to reduce the surface tension of a liquid in which it is dissolved.

Addition of sodium carbonates
Base exchange process

Temporary Hardness

Permanent Hardness

Mg2+ cations in 1 liter of the water (mmole-Eq/L).
On

by the following 2 analytical methods:
By titration with HCl:

determining temporary hardness: 100 ml hard water is taken

ml of the original water sample. Add 3-4 drops

ESTIMATION OF GENERAL HARDNESS BY TITRATION WITH EDTA:

water and changed its color:

Lab # 3 Water Hardness

temporary hardness from total hardness i.e.
Permanent = General hardness

GH = TH + RH

of 7 to 7.5 mmol / L
hardness not

a buret brush, water, and a small amount of

area on a white note card. This will be

full drop of titrant, open the stopcock slightly to

из активированного угля (черные частицы) и катионообменники (гранулы смолы