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Ans:
CHEMISTRY
The branch of science that deals with the properties, composition and structure of matter is called chemistry.
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Q: Write 3 points on the importance of chemistry.
| Write any 3 of these |
IMPORTANCE OF CHEMISTRY
1. Chemistry enables us to design all sorts of materials.
2. Chemistry provides Drugs to fight diseases.
3. Chemistry provides pesticides to protect our health.
4. Chemistry provides Fertilizers to grow our crops.
5. Chemistry provides Fuels for transportation.
6. Chemistry provides Fibres to provide comfort and variety in clothes.
7. Chemistry helps us to understand the nature of our environment and about ourselves.
8. chemistry help us to understand the material world from tiny atom to giant galaxies.
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Ans:
The Greek period The Muslim period
The ROMANS
They also developed little theoretical knowledge
SIR SADIQ’S NOTES FOR IX & X
CHAPTER NO. 1
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
Q: Define laws of chemical combinations.
Ans:
LAWS OF CHEMICAL COMBINATIONS
All the chemical changes are governed by some laws that are known as
laws of chemical combinations
These laws are
1. Law of conservation of mass
2. Law of constant composition Or Law of definite proportions
3. Law of multiple proportions
4. Law of reciprocal proportions.
LAW OF CONSERVATION OF MASS
INTRODUCTION:
A French chemist Lavosier, (1785) found that when a chemical reaction
was carried out in a closed system, the total mass of the system was not
changed. Then Lavosier formulated a law which is known as law of
conservation of mass.
STATEMENT:
It states that,
“Mass is neither created nor destroyed
during a chemical reaction.”
or
“In any chemical reaction the initial
weight of reacting substances is equal
to the final weight of products.”
or
“Total mass of the substance before
reaction is equal to the total mass of
the substance after the reaction.”
or
“Mass is neither created nor destroyed
during a chemical reaction but it only
changes from one form to another”
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
PRACTICAL VERIFICATION (LANDOLT EXPERIMENT)
A German chemist H. Landolt, studied about 15 different chemical
reactions to test validity of the law of conservation of mass,
➢ For this he took a H-shaped tube.
➢ He filled the limb A with AgNO3 (silver nitrate)
➢ And limb B with HCL (hydrochloric acid)
➢ The tube was sealed so that the material could not escape outside.
➢ The tube was weighed initially in a vertical position so the
solutions should not intermix.
➢ The reactants were mixed by shaking and inverting the tube
➢ The tube was weighed after mixing and he observed that weight
remains same.
AgNO3 + HCL
AgCL + HNO3
HCL
AgNO3
LAW OF CONSTANT COMPOSITION.
INTRODUCTION:
This law was presented by a French chemist louis Proust in (1799).
Statement:
It states that,
“Different samples of same compound always
contain the same elements combined together in
the same proportion by mass.”
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
PRACTICAL VERIFICATION (BERZELIUS EXPERIMENT):
He heated 10g of lead (Pb) with various amounts of Sulphur (S). He got
exactly 11.5g of lead sulphide (PbS) and the excess of Sulphur was left
over. When He heated 18g of lead (Pb) with 1.56g of Sulphur (S). He
got exactly 11.5g of lead sulphide (PbS) and the 8g of lead was left
unused.
LAW OF MULTIPLE PROPORTION:
Statement:
It states that,
“When two elements combine with each
other to form two or more compounds, the
ratios of the masses of one element that
combines with the fixed mass of the other
are simple whole numbers”
OR
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
“when two elements combine with each
other to form more than one compound,
the weights of one element that combine
with a fixed weight of the other are in a
ratio of small whole numbers.”
Example:
LAW OF RECIPROCAL PROPORTION
Statement:
It states that
“When two different elements
separately combine with a fixed
mass of a third element, the
proportion in which they combine
with one another shall be either in
the same ratio or some multiple of
it.”
Example:
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
Q: Define the following.
1. ATOMIC MASS
The sum of no. of protons and no. of neutrons present in an atom is
known as atomic mass.
Or
The sum of protons and neutrons present in the nucleus of an atom is
called atomic mass.
➢ Atomic mass is denoted by “A”
➢ Its unit is “a.m.u”
➢ Its formula is “A = P+N”
e.g.:
Atomic mass of carbon © is 12 a.m.u.
Atomic mass of oxygen (O) is 16 a.m.u.
2. MOLECULAR MASS
The sum of atomic masses of all the atoms present in a molecule is
called molecular mass.
➢ Its unit is “a.m.u”.
e.g.
the molecular mass of CO2 is calculated as
molecular mass of CO2 = (12 x 1) + (16 x 2)
= 12 + 32
= 44 a.m.u.
the molecular mass of H2O is calculated as
molecular mass of H2O = (1 x 2) + (16 x 1)
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
= 2 + 16
= 18 a.m.u.
3. FORMULA MASS
The sum of atomic masses of all the atoms present in a formula unit of
the substance is called formula mass.
➢ Its unit is “a.m.u”.
e.g.
the formula mass of NaCl is calculated as
formula mass of NaCl = (23 x 1) + (35.5 x 1)
= 23 + 35.5
= 58.5 a.m.u.
4. MOLAR MASS
The mass (in grams) of one mole of a substance is called molar mass.
or
The mass in grams of one mole of a substance is called molar mass.
➢ Its unit is “a.m.u”.
e.g.
Molar mass of carbon © is 12 a.m.u.
Molar mass of CO2 = (12 x 1) + (16 x 2)
= 12 + 32
= 44 a.m.u.
Molar mass of NaCl = (23 x 1) + (35.5 x 1)
= 23 + 35.5
= 58.5 a.m.u.
5. EMPIRICAL FORMULA (E.F)
The formula which describes the least ratio of all the atoms of each
element present in a molecule is called empirical formula.
E.g.
The E.F of benzene (C6H6) = CH
The E.F of glucose (C6H12O6) = CH2O
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
6. Molecular Formula (M.F)
The formula which shows the actual no. of all the atoms of each
element present in a molecule is called molecular formula.
E.g.
The M.F of benzene = C6H6
The M.F of glucose = C6H12O6
THE M.F OF WATER =H2O
7. MOLE
The molar mass of a substance expressed in gram is called mole.
➢ Its unit is mole
➢ It can be calculated as:
𝑔𝑖𝑣𝑒𝑛 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒
𝑛𝑜. 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 =
𝑚𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒
e.g.
1 mole of carbon © = 12 g
1 mole of carbon-dioxide (co2) = 44 g
1 mole of water (H2O) = 18 g
8. AVOGADRO’S NO. (NA)
The no. of particles present in one mole of a substance is always equal
to 6.02x1023 which is called Avogadro’s no.
Or
The no. of particles (i.e. atoms, ions, molecules, formula units) present
in one mole of a substance Is called Avogadro’s no. which is equal to
6.02x1023
➢ Its symbol is NA
E.g.
1 mole of carbon ©
1 mole of carbon-dioxide (co2)
1 mole of water (H2O)
= 12 g
= 44 g
= 18 g
= 6.02x1023 atoms
= 6.02x1023 atoms
= 6.02x1023 atoms
Q: Define chemical reaction and its types.
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
CHEMICAL REACTION:
The reaction in which the reactants are converted into products is called
a chemical reaction.
TYPES OF CHEMICAL REACTIONS
Chemical reaction is commonly divided into 5 types
1. Decomposition reactions.
2. Addition reaction (combination reaction).
3. Single displacement reaction.
4. Double displacement reaction.
5. Combustion reaction.
DECOMPOSITION REACTION
A reaction in which a chemical substance breaks down to form two or
more simpler substances is called a decomposition reaction.
• The general form for a decomposition reaction is: AB → A + B.
• Decomposition reactions are also known as analysis reactions or
chemical breakdowns.
Example,
Calcium carbonate decomposes into calcium oxide and carbon-dioxide in
presence of heat
heat
CaCO3
CaO + CO2
ADDITION OR COMBINATION REACTION:
A reaction in which two or more substances combine to form a single
substance is called an addition or combination reaction.
• These reaction are reverse of decomposition reactions.
For example:
Calcium oxide (CaO) reacts with carbon dioxide (CO2) TO form calcium
carbonate (CaCO3).
CaO + CO2
CaCO3
SINGLE REPLACEMENT (DISPLACEMENT) REACTION:
A reaction in which one atom or group of atoms of a compound replaced
by another atom or group of atoms is defined as displacement reaction.
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
Example:
Zinc replaces hydrogen in hydrogen chloride (HCI) to give zinc chloride
Zn + 2HCL
ZnCL2 + H2
DOUBLE DISPIACEMENT REACTION
The reaction in which two compounds exchange their partners, so that
two new compounds are formed is known as Double Displacement
Reaction.
Example:
When sodium chloride (NaCl) is reacted with silver nitrate (AgNO 3)
solution, they exchange their partners to form two different compounds
silver chloride (AgCl) and sodium nitrate (NaNO3)
NaCL + AgNO3
NaNO3 + AgCl
COMBUSTION REACTION
A reaction in which substances react with either free oxygen or Oxygen
of the air, with the rapid release of heat and flame, is called Combustion
reaction.
For example,
when methane (CH4), gas burns in air, it forms carbon dioxide gas
(CO2) water (H20) and heat.
CH4 + 2O2
CO2 + 2H2O
Similarly, when carbon (C) burns in air, it produces carbon dioxide
(CO2) gas and heat.
C+O
CO2 + HEAT
Q: Define chemical equation.
Ans:
A chemical equation represents the chemical change or reaction showing
reactants on the left side of an arrow and products on the right. The
equation is balanced by placing co-efficient in front of the formulas, so
the number of atoms of each element are same on each side of an
arrow.
PREPARED AND
COMPOSED BY
Historical development of chemistry consists of following three periods.
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The Modern Period
1. THE GREEK PERIOD
The Greek Philosophers like
Plato (347-428 BC),
Aristotle (322-384 BC),
Democritus (357-460 BC)
contributed a lot to the early development of chemistry. They introduced the concept of elements, atoms and the chemical reactions.
They thought that all matter was derived from four elements.
Earth: Earth was dry and cold.
Fire: Fire was hot and dry
Air: Air was cold, wet and hot
Water: Water was cold, hot and wet
They developed the chemical arts.
They improved metallurgical processes and introduced the enameling of poetry
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SIR SADIQ’S NOTES FOR IX & X
CHAPTER NO. 1
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
Q: Define laws of chemical combinations.
Ans:
LAWS OF CHEMICAL COMBINATIONS
All the chemical changes are governed by some laws that are known as
laws of chemical combinations
These laws are
1. Law of conservation of mass
2. Law of constant composition Or Law of definite proportions
3. Law of multiple proportions
4. Law of reciprocal proportions.
LAW OF CONSERVATION OF MASS
INTRODUCTION:
A French chemist Lavosier, (1785) found that when a chemical reaction
was carried out in a closed system, the total mass of the system was not
changed. Then Lavosier formulated a law which is known as law of
conservation of mass.
STATEMENT:
It states that,
“Mass is neither created nor destroyed
during a chemical reaction.”
or
“In any chemical reaction the initial
weight of reacting substances is equal
to the final weight of products.”
or
“Total mass of the substance before
reaction is equal to the total mass of
the substance after the reaction.”
or
“Mass is neither created nor destroyed
during a chemical reaction but it only
changes from one form to another”
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
PRACTICAL VERIFICATION (LANDOLT EXPERIMENT)
A German chemist H. Landolt, studied about 15 different chemical
reactions to test validity of the law of conservation of mass,
➢ For this he took a H-shaped tube.
➢ He filled the limb A with AgNO3 (silver nitrate)
➢ And limb B with HCL (hydrochloric acid)
➢ The tube was sealed so that the material could not escape outside.
➢ The tube was weighed initially in a vertical position so the
solutions should not intermix.
➢ The reactants were mixed by shaking and inverting the tube
➢ The tube was weighed after mixing and he observed that weight
remains same.
AgNO3 + HCL
AgCL + HNO3
HCL
AgNO3
LAW OF CONSTANT COMPOSITION.
INTRODUCTION:
This law was presented by a French chemist louis Proust in (1799).
Statement:
It states that,
“Different samples of same compound always
contain the same elements combined together in
the same proportion by mass.”
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
PRACTICAL VERIFICATION (BERZELIUS EXPERIMENT):
He heated 10g of lead (Pb) with various amounts of Sulphur (S). He got
exactly 11.5g of lead sulphide (PbS) and the excess of Sulphur was left
over. When He heated 18g of lead (Pb) with 1.56g of Sulphur (S). He
got exactly 11.5g of lead sulphide (PbS) and the 8g of lead was left
unused.
LAW OF MULTIPLE PROPORTION:
Statement:
It states that,
“When two elements combine with each
other to form two or more compounds, the
ratios of the masses of one element that
combines with the fixed mass of the other
are simple whole numbers”
OR
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
“when two elements combine with each
other to form more than one compound,
the weights of one element that combine
with a fixed weight of the other are in a
ratio of small whole numbers.”
Example:
LAW OF RECIPROCAL PROPORTION
Statement:
It states that
“When two different elements
separately combine with a fixed
mass of a third element, the
proportion in which they combine
with one another shall be either in
the same ratio or some multiple of
it.”
Example:
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
Q: Define the following.
1. ATOMIC MASS
The sum of no. of protons and no. of neutrons present in an atom is
known as atomic mass.
Or
The sum of protons and neutrons present in the nucleus of an atom is
called atomic mass.
➢ Atomic mass is denoted by “A”
➢ Its unit is “a.m.u”
➢ Its formula is “A = P+N”
e.g.:
Atomic mass of carbon © is 12 a.m.u.
Atomic mass of oxygen (O) is 16 a.m.u.
2. MOLECULAR MASS
The sum of atomic masses of all the atoms present in a molecule is
called molecular mass.
➢ Its unit is “a.m.u”.
e.g.
the molecular mass of CO2 is calculated as
molecular mass of CO2 = (12 x 1) + (16 x 2)
= 12 + 32
= 44 a.m.u.
the molecular mass of H2O is calculated as
molecular mass of H2O = (1 x 2) + (16 x 1)
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
= 2 + 16
= 18 a.m.u.
3. FORMULA MASS
The sum of atomic masses of all the atoms present in a formula unit of
the substance is called formula mass.
➢ Its unit is “a.m.u”.
e.g.
the formula mass of NaCl is calculated as
formula mass of NaCl = (23 x 1) + (35.5 x 1)
= 23 + 35.5
= 58.5 a.m.u.
4. MOLAR MASS
The mass (in grams) of one mole of a substance is called molar mass.
or
The mass in grams of one mole of a substance is called molar mass.
➢ Its unit is “a.m.u”.
e.g.
Molar mass of carbon © is 12 a.m.u.
Molar mass of CO2 = (12 x 1) + (16 x 2)
= 12 + 32
= 44 a.m.u.
Molar mass of NaCl = (23 x 1) + (35.5 x 1)
= 23 + 35.5
= 58.5 a.m.u.
5. EMPIRICAL FORMULA (E.F)
The formula which describes the least ratio of all the atoms of each
element present in a molecule is called empirical formula.
E.g.
The E.F of benzene (C6H6) = CH
The E.F of glucose (C6H12O6) = CH2O
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
6. Molecular Formula (M.F)
The formula which shows the actual no. of all the atoms of each
element present in a molecule is called molecular formula.
E.g.
The M.F of benzene = C6H6
The M.F of glucose = C6H12O6
THE M.F OF WATER =H2O
7. MOLE
The molar mass of a substance expressed in gram is called mole.
➢ Its unit is mole
➢ It can be calculated as:
𝑔𝑖𝑣𝑒𝑛 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒
𝑛𝑜. 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 =
𝑚𝑜𝑙𝑎𝑟 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒
e.g.
1 mole of carbon © = 12 g
1 mole of carbon-dioxide (co2) = 44 g
1 mole of water (H2O) = 18 g
8. AVOGADRO’S NO. (NA)
The no. of particles present in one mole of a substance is always equal
to 6.02x1023 which is called Avogadro’s no.
Or
The no. of particles (i.e. atoms, ions, molecules, formula units) present
in one mole of a substance Is called Avogadro’s no. which is equal to
6.02x1023
➢ Its symbol is NA
E.g.
1 mole of carbon ©
1 mole of carbon-dioxide (co2)
1 mole of water (H2O)
= 12 g
= 44 g
= 18 g
= 6.02x1023 atoms
= 6.02x1023 atoms
= 6.02x1023 atoms
Q: Define chemical reaction and its types.
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
CHEMICAL REACTION:
The reaction in which the reactants are converted into products is called
a chemical reaction.
TYPES OF CHEMICAL REACTIONS
Chemical reaction is commonly divided into 5 types
1. Decomposition reactions.
2. Addition reaction (combination reaction).
3. Single displacement reaction.
4. Double displacement reaction.
5. Combustion reaction.
DECOMPOSITION REACTION
A reaction in which a chemical substance breaks down to form two or
more simpler substances is called a decomposition reaction.
• The general form for a decomposition reaction is: AB → A + B.
• Decomposition reactions are also known as analysis reactions or
chemical breakdowns.
Example,
Calcium carbonate decomposes into calcium oxide and carbon-dioxide in
presence of heat
heat
CaCO3
CaO + CO2
ADDITION OR COMBINATION REACTION:
A reaction in which two or more substances combine to form a single
substance is called an addition or combination reaction.
• These reaction are reverse of decomposition reactions.
For example:
Calcium oxide (CaO) reacts with carbon dioxide (CO2) TO form calcium
carbonate (CaCO3).
CaO + CO2
CaCO3
SINGLE REPLACEMENT (DISPLACEMENT) REACTION:
A reaction in which one atom or group of atoms of a compound replaced
by another atom or group of atoms is defined as displacement reaction.
PREPARED AND
COMPOSED BY
�SIR SADIQ’S NOTES FOR IX & X
Example:
Zinc replaces hydrogen in hydrogen chloride (HCI) to give zinc chloride
Zn + 2HCL
ZnCL2 + H2
DOUBLE DISPIACEMENT REACTION
The reaction in which two compounds exchange their partners, so that
two new compounds are formed is known as Double Displacement
Reaction.
Example:
When sodium chloride (NaCl) is reacted with silver nitrate (AgNO 3)
solution, they exchange their partners to form two different compounds
silver chloride (AgCl) and sodium nitrate (NaNO3)
NaCL + AgNO3
NaNO3 + AgCl
COMBUSTION REACTION
A reaction in which substances react with either free oxygen or Oxygen
of the air, with the rapid release of heat and flame, is called Combustion
reaction.
For example,
when methane (CH4), gas burns in air, it forms carbon dioxide gas
(CO2) water (H20) and heat.
CH4 + 2O2
CO2 + 2H2O
Similarly, when carbon (C) burns in air, it produces carbon dioxide
(CO2) gas and heat.
C+O
CO2 + HEAT
Q: Define chemical equation.
Ans:
A chemical equation represents the chemical change or reaction showing
reactants on the left side of an arrow and products on the right. The
equation is balanced by placing co-efficient in front of the formulas, so
the number of atoms of each element are same on each side of an
arrow.
PREPARED AND
COMPOSED BY
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