MUHAMMAD FAHAD ANSARI 12IEEM 14

1. Acid-Base Chemistry
MUHAMMAD FAHAD ANSARI
12IEEM 14

2. • Centuries ago chemists began to classify substances by grouping them
into elements, compounds, and mixtures.
• Then the elements were classifies further into metals and nonmetals.
Likewise, compounds were divided into organic and inorganic.
• The organic compounds were eventually grouped into smaller classes
such as alcohol, hydrocarbons, ketones, ethers, and so on.
• The inorganic compounds were classified on the basis of their properties
such as atomic structure and the bonding these were further classified as
acids, bases, slats and so on.

3. Chemical Substances in
Environment

4. Major Groups (Classes) of
Chemical Substances

5. Inorganic Compounds
Acids, Bases and Buffers

6. Importance

7. Acids, bases, and buffers are important to the functioning of the human
body and are also of tremendous importance to industry and commerce.
Many foods we eat either contain acids or yield acids as they are
digested.
Yet the acid base balance of your body blood must be maintained with
very narrow limits, or you will die. The concentration of H+ (acidity) of the
blood should be approximately 4X10-8 M.
• If it increases to approximately 6X10-8 M
• Or decreases to approximately 2.5X10-8 M death results
So that, blood acidity is maintained at the proper level.

8. What are the Acids and
Bases ?
• Theories,
• Properties and
• Their Composition

9. Theories about Acids
 Santé Arrhenius (1859-1927)
Swedish chemist explains why water solutions of certain
substances conduct electricity.
 Arrhenius proposed the theory of ionization (Electrolytes).
• He suggested that these substances, which are called
electrolytes, dissociate in water to produce charged particles
(ions), ions conduct electricity. So that Acids are electrolytes.
And when Acid react with metals to yield hydrogen gas (H2).

10.  Arrhenius defined acids as substances that ionize in water to yield
hydrogen ions (H+)
• The thing common to all acids is their ability to yield hydrogen ions (H+) in
water.
• For example:
• HCl in H2O  Yields H+ + Cl-
• HF in H2O  H+ + F-
• HBr in H2O  H+ + Br-

11.  Bronsted-Lowry Concept about Acids:
According to this theory, acids are defined simply as proton
donors.
The hydrogen ion is a proton: the hydrogen atom minus its
electron.
So acid-base reactions are not limited to reactions between
water solutions, as defined by Arrhenius.
Lowry; defines any substance which gives up a proton
(hydrogen ion H+) in any reaction is an acid. This includes all
the substances those are acids according to the Arrhenius
concept and many others.

12. Properties of Acids
Physical State
The acids occur in all three physical states
(gases, liquids, and solids)
• Hydrochloric acid as a gas,
• Acetic acid as a liquid and
• Boric acid as a solid

13. • Acids have a sour taste. For example, the sour taste of
lemons and other citrus fruits is to due to citric acid, one of
the organic acids.
• Acids react with active metals to yield hydrogen. Sodium
(Na), potassium (K), calcium (Ca), zinc (Zn), and other active
metals react with acids such as hydrochloric and sulfuric to
yield hydrogen gas.
• Acids react with bases to yield a salt and water. Bases and
salts are two other major classes of inorganic compounds.
Hydrochloric acid (HCl) reacts with the base sodium hydroxide
(NaOH) to yield ordinary table salt, which is sodium chloride
(NaCl), and water.

14. • Acids are electrolytes; they conduct electricity when
dissolved in water. However, in the liquid state pure acid
compounds such as HCl do not conduct electricity.
• Acids turn blue litmus red. Litmus is an organic dye that is
used as an indicator. It becomes red when exposed to acids
and blue when exposed to bases, so it is a convenient way to
distinguish between acids and bases.

15. Acids Composition (Elemental)
• In terms of composition, acids consist of the nonmetallic element,
hydrogen covalently bonded to other nonmetallic element.
• The system of naming, the acids centers around the number of
oxygen atoms present.
• The most common oxygen containing acids of the nonmetal has three
oxygen atoms include halogens (Cl, Br, I) nitrogen (N), and carbon (C).
For Example: HClO3 chloric acid, HBrO3 bromic acid, HIO3 iodic acid, HNO3
nitric acid and H2CO3 carbonic acid.

16. • Acids of sulfur ( S ) and phosphorous ( P ) contain four oxygen atoms
H2SO4 sulfuric acid and H3PO4 phosphoric acid.
• Only sulfur and phosphorous contain four oxygen atoms the rest contain
three oxygen atoms.
• The number of hydrogen atoms is the same in all the acids of a
given nonmetal.
• Acids of phosphorous contain three hydrogen atoms. The acids of sulfur
and carbon contain two hydrogen atoms, all the rest contain only one
hydrogen atom.

17. Bases
• Theories,
• Composition and
• Properties

18.  Arrhenius considered bases to be substances that ionize
in water to yield hydroxide ions (OH-)
• The common bases are metallic hydroxides such as NaOH
sodium hydroxide, calcium hydroxide Ca(OH-)2. The metallic
hydroxide bases are solids that will conduct electricity in
molten state-ionically bonded.
• NaOH in water  Na+ + OH-
• Ca (OH-)2 in water Ca2+ + 2OH-
• NH3 + H2O  NH4OH  NH4+ + OH-
(nonmetallic hydroxide)

19.  Lowry, defines bases as protons (H+)
acceptors.
Water acts as a base in the presence of an acid. It accepts a
proton (H+) from HCl and becomes a hydronium ion (H3O+).
HCl + H2O  H3O+ + Cl-
Hydronium ion can give up the proton (H+) and the chloride
ion (Cl-) can accept a proton, they are also an acid and base,
respectively.
NH3 + H2O = ( ) = NH4+ + OH-

20. Composition of Bases (Elemental)
• The bases are named by simply naming the metal and adding
the word hydroxide, such as sodium hydroxide (NaOH),
calcium hydroxide Ca (OH-)2, and aluminum hydroxide
Al(OH)3, are the more common bases of the non-transition
metals.
• Lowry Concept: the solvent enters into the reaction, and the
acids and bases occur in solution are called conjugate pairs.
The hydronium ion is the conjugate acid of the base water,
and the chloride ion is the conjugate base of the acid HCl.

21. • Many transition metals may lose varying number of
electrons as they react to form compounds.
• Metals may have more then one oxidation number.
• For example, copper (Cu) may lose one or two
electrons, forming two different ions: Cu1+, Cu2+. [Cu
OH and Cu (OH-)2] are possible.

22. Salts
Much of the earth’s crust consists of salts.
Acids react with bases to form salts and water.
HCl + NaOH  NaCl + H2O

23. Composition and Properties of Salts
• In general, most inorganic salts consist of a metallic element
ionically bonded to the nonmetallic element or one of the
oxygen containing ions (SO42-, CO32-, NO3- and so on) of the
nonmetallic element.
• The properties of the salts are essentially the same as those
of the ionically bonded compounds.
• The salts are crystalline solids that have high melting and
boiling points, and they are electrolytes. They are generally
more soluble in water and more stable to heat than the
organic compounds.

24. • In general binary salts are more stable to heat than the
ternary salts.
• The N-to-H bonds in the ammonium ions (NH4+) are covalent,
as are the bonds between oxygen and other nonmetals.

25. Acid-Base Reactions

26. Acid-Base and Oxidation-Reduction
Reactions
• An acid-base reaction is characterized by the exchange of
protons (H+) between reactants. One substance the acid,
gives up protons; another substance, the base, gains the
protons.
• In oxidation-reduction reaction is characterized by the
exchange of electron between reactants, one substance
loses electrons (or share them more freely) and another
substance gains the electrons (or increase its share of them)

27. Acids and Bases in Water
• Na+OH- + H+NO3-  Na+NO3- + H2O
(aq) (aq) (aq)
base acid salt water
• NH3 + HCl  NH4+Cl-
(gas) (gas) (solid)
base acid salt

28. Solutions in water are called aqueous solution.
• HCl (in water)  H+ + Cl-
• Na+OH- (in water)  Na+ + OH-
• H2O + HCl  H3O+ + Cl-
base acid acid base
The hydronium ion (H3O+) is capable of giving up the proton
(to the base) and becoming a water molecule again, it is an
acid. Thus the hydronium ion is the conjugate acid of the
base water.

29. Substances other than metallic hydroxides that are bases
when dissolved in water
• NH3 + H2O <==> NH4+ + OH-
base acid acid base

30. Acids of Halogens and Other
Elements
The acids of Chlorine, Iodine, Fluorine, and Bromine
• HClO4 Perchloric acid
• HClO3 Chloric acid
• HClO2 Chlorous acid
• HClO Hypochlorous acid
• HCl Hydrochloric acid
• HI Hydroiodic acid
• HF Hydrofluoric acid
• HBr Hydrobromic acid

31. Acids of Nitrogen
• HNO3 Nitric acid
• HNO2 Nitrous acid
Acids of Carbon
• H2CO3 Carbonic acid
Acids of Sulfur
• H2SO4 Sulfuric acid
• H2SO3 Sulfurous acid
Acids of Phosphorous
• H3PO4 Phosphoric acid
• H3PO3 Phosphorous acid

32. Bases
Bases of non-transition elements
• Li, Na, K (OH-)
• Ba, Ca, Mg (OH-)2
• Al (OH-)3
Bases of transition elements
• Cu1+OH-
• Cu2+(OH-)2
• Fe2+ (OH-)2
• Fe3+ (OH-)3

33. Oxides
• Oxygen is a special element when combined with hydrogen; it forms the
very important compound water (hydrogen oxide).
• If one hydrogen of water is displaced by a metallic element, the hydroxide
(OH-) bases result.
• Oxygen also combines with both the metallic and nonmetallic elements
to form other binary (two-element) compounds.
• Many of these compounds are salts (compounds of metal and
nonmetal), however, because of oxygen special role they are often
classified as oxides.

34. Metallic Oxides
• Oxygen readily combines with the metallic elements to form
compounds, most of which are ionically bonded.
Properties of Metallic Oxides
The metallic oxides have the same general properties as other ionically
bonded compounds. They are solids with high melting and boiling points
and high heat stability.
• Na2O + H2O  2NaOH
• CaO + H2O  Ca (OH-)2

35. Nonmetallic Oxides
• Oxygen bonds covalently with the other nonmetallic elements to form
oxides.
• A given nonmetallic element may form more than one oxide, partly
because oxygen may bond to the element by both covalent and co-
ordinate covalent bonds.
• System of naming oxides of the nonmetallic elements is as following:
• CO carbon monoxide CO2 carbon dioxide
• SiO2 silicon dioxide SO2 sulfur dioxide
• SO3 sulfur trioxide N2 O 3 dinitrogen trioxide
• P2O5 diphosphrous Pentoxide

36. Properties of Nonmetallic Oxides
• The nonmetallic oxides may be considered to be anhydrides
of acids. They form acid in water, the soluble nonmetallic
oxides are electrolytes.
• CO2 + H2O = H2CO3 in (H2O) = H3O+ + HCO3-
• SO2 + H2O = H2SO3 in (H2O) = H3O+ + HSO3-