1. Significance
of Acids ,
Bases &salts

2. Acids
• an acid is a chemical substance whose aqueous solutions are
characterized by a sour taste, the ability to turn blue litmus red, and
the ability to react with bases and certain metals (like calcium) to
form salts. Aqueous solutions of acids have a pH of less than 7. A
lower pH means a higher acidity, and thus a higher concentration
of hydrogen ions in the solution. Chemicals or substances having the
property of an acid are said to be acidic.
• There are three common definitions for acids: the Brønsted-Lowry
definition, and the Lewis definition. The Arrhenius definition defines
acids as substances which increase the concentration of hydrogen
ions (H+), or more accurately, hydronium ions (H3O+), when dissolved
in water. The Brønsted-Lowry definition is an expansion: an acid is a
substance which can act as a proton donor. By this definition, any
compound which can easily bedeprotonated can be considered an
acid. Examples include alcohols and amines which contain O-H or N-H
fragments. A Lewis acid is a substance that can accept a pair of
electrons to form a covalent bond. Examples of Lewis acids include all
metal cations, and electron-deficient molecules such as boron
trifluoride and aluminium trichloride.

3. Properties of acids
• A characteristic sour taste
• ability to change the color of
litmus paper from blue to red
• react with certain metals to
produce gaseous H2
• react with bases to form a salt
and water.

4. Bases
• In chemistry, a base is a substance that, in aqueous solution, is
slippery to the touch, tastes bitter, changes the colour of
indicators (e.g., turns red litmus paper blue), reacts with acids to
form salts, and promotes certain chemical reactions (base
catalysis). Examples of bases are the hydroxides of
the alkali andalkaline earth metals (NaOH, Ca(OH)2, etc). Such
substances produce hydroxide ions (OH-) in aqueous solutions,
and are thus classified as Arrhenius bases.
• Bases can be thought of as the chemical opposite of acids. Bases
and acids are seen as opposites because the effect of an acid is to
increase thehydronium(H3O+) concentration in water, whereas
bases reduce this concentration. A reaction between an acid and
base is called neutralization. In a neutralization reaction, an
aqueous solution of a base reacts with an aqueous solution of an
acids to produce a solution of water and salt in which the salt
separates into its component ions. If the aqueous solution
is saturated with a given salt solute, any additional such
salt precipitates out of the solution

5. Properties of bases
• Bases change red litmus paper to bl
ue. This is just the opposite of thech
ange which acids cause in litmus pap
er
• Bases possess a bitter taste and feel
soapy when in contact with the skin.
• Bases react with acids to form salts a
nd water (neutralization reaction).
• This is the same type reaction as pre
viously discussed under acids

6. salts
• In chemistry, salts are ionic compounds that result from
the neutralization reaction of an acid and a base. They
are composed of related numbers
of cations (positively charged ions) and anions (negative
ions) so that the product is electrically neutral (without a
net charge). These component ions can be inorganic such
as chloride (Cl−), as well as organic such
as acetate (C2H3O2
−) andmonatomic ions such as fluoride
(F−), as well as polyatomic ions such as sulfate (SO4
2−).
• There are several varieties of salts. Salts that hydrolyze to
produce hydroxide ions when dissolved in water are basic
salts and salts that hydrolyze to produce hydronium ions
in water are acid salts. Neutral salts are those that are
neither acid nor basic salts.Zwitterions contain an anionic
center and a cationic center in the same molecule but are
not considered to be salts. Examples include amino acids,
many metabolites, peptides, and proteins.

7. Properties of salts
• Ionic compounds are composed of a cation
(positively charged atom) and an anion
(negatively charged atom) in an orderly
arrangement. The three dimensional
arrangement of atoms or ions in a crystal is
referred to as crystal lattice. The crystal
lattices of sod
• The simplest repeating unit of a crystal is
known as a unit cell. Both NaCl and CsCl
are classified as part of a cubic crystal
system. The unit cells of NaCl and CsCl are
different because their ions have different
sizes. Three different ways that atoms can
arrange themselves in a cubic crystal
system are shown below. ium chloride and
cesium chloride are shown below.

8. PH values

9. Thank you