Types of Chemical Reactions

compounds and their properties

compound is represented by its chemical formula, a notation that

uses atomic symbols with numerical subscripts to convey the relative proportion of atoms of different elements in the substance.

E. g. HCl, H2O, NH3

There are three fundamental kinds of chemical bonds between atoms - covalent bonds, ionic bonds and metallic bonds.

the elements changes on crossing from left to right in

the row of the Periodic Table from potassium to bromine?
K to Ca Sc to Zn Ga to Br
A decrease increase decrease
B decrease decrease increase
C decrease decrease decrease
D increase decrease increase
E increase increase increase

given below corresponds to the Mg2+ ion (in its ground

state)?
A. Is22s22p63s23p2
B. Is22s22p63s2
C. Is22s22p6
D. Is22s22p63s1
E. Is22s22p53s1

as each of lithium, sodium and potassium reacts with water.

b

State the difference in the reactivity of these alkali metals with water.

с Describe what you could do experimentally to show what the product(s) are.

for a lithium compound?
A Li2S
B LiCO3
C CH3CO2Li
D LiHSO4
E Li3N

or inorganic. Organic compounds are those formed by carbon and

hydrogen (hydrocarbon) or carbon and hydrogen together with oxygen, nitrogen, and a few other elements.

Inorganic compounds are compounds composed of elements other than carbon. Except a few simple compounds of carbon, including carbon monoxide, carbon dioxide, carbonates and cyanides are generally considered to be inorganic.

that chemists use to identify compounds. Two classes of names

exist: common names and systematic names. Common names: ammonia, water, baking soda, laughing gas, muriatic acid, table salt

Systematic names precisely identify the chemical composition of the compound. The present system of inorganic chemical nomenclature was devised by the International Union of Pure and Applied Chemistry (IUPAC).

HCl(aq) CuCl2, HNO3 Cl2O7 BaSO4 KNO3

H2SiO3 NH4Cl H2SO4 NaHCO3 (CuOH)2CO3

2. Write the formulas
diphosphorus trioxide, iron dichloride, hydrogen sulfide, phosphoric acid, ammonia, sodium nitrite, phosphine, sulfurous acid, aluminium hydroxide, potassium dihydrocarbonate, sodium dichromate, sodium hexahydroxogermanate

amphoteric (react with both acids and alkalis)?
Al2O3 Cl2O7 CO2

HCl H3PO4 K2O KOH MgO
Na2O NO2 P4O10 SiO2 SO2
A. Acidic = 10; Amphoteric = 2; Alkaline = 4
B. Acidic = 7; Amphoteric = 1; Alkaline = 5
C. Acidic = 9; Amphoteric = 2; Alkaline = 2
D. Acidic = 6; Amphoteric = 1; Alkaline = 6
E. Acidic = 8; Amphoteric = 1; Alkaline = 4

gas

Formation of a precipitate

Color change

Emission of odor

should be balanced.
Sulfur reacts with oxygen to form/to give sulfur

dioxide.
One mole of sulfur reacts with one mole of oxygen forming/giving one mole of sulfur dioxide.
Sulfur, a yellow solid, burns forming a colorless gas with an irritating smell.

sulfur + oxygen  sulfur dioxide
S(s) + O2(g)  SO2(g)

combine to produce a more complex substance.
AKA: Combination reaction.
A +

B  AB

HINT: only one product.

Examples of Synthesis Reactions
CO2 + H2O  H2CO3
4Fe + 3O2  2Fe2O3
Li2O + H2O  2LiOH

down into two or more simpler substances.
Heat is often used

to aid in decomposition reactions – these reactions that employ heat are called thermal decompositions.
Decompositions and synthesis reactions are opposites.
AB  A + B
HINT: only one reactant, two or more products.

Examples of Decomposition Reactions:
NH4NO3  N2O + 2H2O
Ca(OH)2  CaO + H2O
2H2O2  2H2O + O2

place of one of the elements in a compound.
AKA: Single

Replacement
AB + Z  ZB + A
Metals displace metals while nonmetals displace nonmetals.
HINT: The single mysterious loner moves into town and breaks up the happy couple!

Examples of Single Displacement Reactions
Fe + CuSO4  FeSO4 + Cu
2K + MgO  K2O + Mg
2CuF + Ba  BaF2 + 2Cu

is a list of metals and hydrogen that are arranged

in order of reactivity.

Li K Ba Ca Na Mg Al Zn Fe Ni Sn Pb H Cu Hg Ag Au

The rule is that the element can only be displaced by another element that is to the left of it. This makes Lithium the strongest and Gold the weakest.

There is also a halogen activity series – it is used to predict reactions with halides.
F Cl Br I

three ways:
Straight forward Single Displacements
Reactions with Acids
Reactions with Water
Straight Forward

Single Displacements
Use the rule of “whoever is more to the left wins” to see if there is a reaction or not.
Reactions with Acids
Acids contain hydrogen (positive like the metals). If you are to the left of hydrogen – you react and take its place – if you are to the right – there is no reaction.
Reactions with Water
Only the first five elements (Li K Ba Ca Na) will react with water. It will form a hydroxide and hydrogen gas.

partners with each other.
Again, positive ions switch with positive ions

(and/or vice-versa).
AB + XY  AY + XB
HINT: Two couples switch partners at the dance.

Examples of Double Displacement Reactions:
Pb(NO3)2 + 2KI  PbI2 + 2KNO3
Na2SO3 + 2HCl  2NaCl + H2SO3
2NaOH + H2SO4  2H2O + Na2SO4

– some compounds form products that break down further into

gases.
Water – results from a neutralization between an acid and a base.

Pb(NO3)2(aq) + K2CrO4(aq)  PbCrO4(s) + 2KNO3(aq)

very rapidly with oxygen to form carbon dioxide and water.
Combustion

reactions release a good deal of energy in a very short period of time.
Fuel + O2  CO2 + H2O
HINT: Something combines with oxygen to produce carbon dioxide and water.
C10H8(s) + 12O2 (g)  10CO2 (g) + 4H2O(g)

may result in an incomplete combustion.
The products of an incomplete

combustion are water, carbon dioxide, carbon monoxide and carbon (a solid residue).
The general equation is:
Fuel + O2  H2O + CO2 + CO + C

O2  MgO

H2O2  H2O + O2

Al + CuCl2 

Cu + AlCl3

Pb(NO3)2 + KI  PbI2 + KNO3

SO2, H2O, CO2, N2O5, NO, N2O are common non metal

oxides, they have covalent bond structure.
Na2O, FeO, Al2O3, CaO, SiO2, MgO, CuO, PbO are some common metal oxides they have ionic structure.

Naming of Oxides
They are named like binary compounds.
MgO : Magnesium oxide
SO2 : Sulfur dioxide
P2O5 : Diphosphorus pentoxide
SnO2 : Tin(IV) oxide

non metals are called acidic oxides. SO2, NO2, P2O5, Cl2O

are examples.
Their solutions are acidic. They are known as acidic anhydrides.
Acidic oxide + water → Acid P2O5 + 3H2O → 2H3PO4
2. Basic Oxides
Generally metal oxides are called basic oxides. Na2O, CaO, MgO are examples.
Their solutions are basic. They are known as basic anhydrides.
Basic oxide + water → Base MgO + H2O → Mg(OH)2
3. Mixed Oxides
Compounds that contain two oxides of the same metal are called mixed oxides. Fe3O4, Mn3O4, Pb3O4 are examples. They behave as if they are two separate oxides in chemical reactions.
Fe3O4 : FeO*Fe2O3 : Iron (II, III) oxide

bases.
They have slippery feeling. Many cleaning products contain bases.

NaOH(s) → Na+(aq) + OH-(aq)

Naming of Bases
The word “hydroxide” is added after the name of metal ion in the naming of bases.
Mg(OH)2 : Magnesium hydroxide
KOH : Potassium hydroxide
NaOH : Sodium hydroxide
Ba(OH)2 : Barium hydroxide

in water completely are said to be strong base. NaOH,

KOH and LiOH are strong bases (alkalis).
Bases that ionize in water partially are called weak bases. Fe(OH)2, Al(OH)3 are example for weak bases.

Chemical Properties of Bases
According to solubility bases conduct electricity.
change the color of litmus paper to blue.
react with acids and produce salt and water.
Water insoluble bases decompose on heating to give metal oxides and water.
2KOH(s) + H2SO4(l) → K2SO4(aq) + 2H2O(l)
Mg(OH)2 → MgO + H2O
 

acids.
HCl(g) → H+(aq) + Cl-(aq)

H2SO4 → 2H+(aq) + SO4-2(aq)
• They have sour taste.
They change the color of litmus paper to red.
Their aqueous solutions conduct electricity.
They are corrosive substances.
Most of them are soluble in water.
Naming of Acids
Acids containing two types of atoms are called binary acids. Their names follow the form hydro + nonmetal name + –ic + acid.
HCl : Hydrochloric acid
Acids containing oxygen atoms are called oxy acids. Their names follow the form –ic + acid, or –ous + acid.
HNO3 : Nitric acid HNO2 : Nitrous acid
 

ionizes completely, it is an strong acid, and if it

ionizes partially it is a weak acid.
Strong acids HCl, H2SO4, HNO3
Weak acids H2SO3, HNO2, H2S, HCN
According to Number of Hydrogen Atoms
According to number of H+ ion produced acids are classified as monoprotic, diprotic or triprotic.
Monoprotic acids HCl, HNO3, HI, HBr, HClO4
Diprotic acids H2SO3, H2S, H2CO3, H2SO4
Triprotic acids H3PO4

conduct electricity, during the ionization heat is released.
• They

change the color of indicators.
• They react with bases and produce salt and water, it is called neutralization reaction.
They react with basic oxides and some salts.
• They react with some metals and produce hydrogen gas.
HNO3(l) + KOH(s) → KNO3(aq) + H2O(l)
2HCl(aq) + Zn(s) → ZnCl2(aq) + H2(g)
 

Sn, Pb, and Be are amphoteric compounds. Oxides and hydroxides

of these metals have both acidic and basic characters.
They are insoluble in water and do not react with it.
 
ZnO, Al2O3 are oxides, and Zn(OH)2, Al(OH)3 are hydroxides.
ZnO + 2HCl → ZnCl2 + H2O
ZnO + 2NaOH → Na2ZnO2 + 2H2O

or basicity of an aqueous solution. It is approximately the

negative of the logarithm to base 10 of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion.

pH = - lg [H+]

ZnBr2, FeSO4…etc
• They are all crystalline solids.
• They have

high melting and boiling points.
• Many of them are soluble in water and their aqueous solutions conduct electricity.

Naming of Salts
In the naming of salts first metal ion (positive ion) then name of negative ion is read.
KMnO4 Potassium permanganate

of strong acids with strong bases.
NaCl, LiNO3, KNO3, Li2SO4

.

B. Acidic Salts
are formed from the reactions of strong acids with weak bases. Their solutions are acidic.
FeCl2, Zn(NO3)2

C. Basic Salts
are formed from the reactions of weak acids with strong bases. Their solutions are basic.
NaCN, LiF, K2CO3, K2C2O4
 

activity strength.
Zn(s) + 2AgNO3(aq) → 2Ag(s) + Zn(NO3)2(aq)

Water soluble salts undergo displacement reaction.
KCI(aq) + AgNO3(aq) → 2AgCl(s) + KNO3(aq)
They may also react with acids under certain conditions.
2HCI + CaCO3 → CaCl2 + H2O + CO2