Download Document

CHAPTER 1
INTRODUCTION TO CHEMISTRY
DEFINATION OF CHEMISTRY
Chemistry is the branch of science that deals with the properties, composition
and structure of matter.
BRANCHES OF CHEMISTRY
There are various branches of chemistry. The main branches of chemistry are
PHYSICAL CHEMISTRY
ORGANIC CHEMISTRY
INORGANIC CHEMISTRY
ANALYTICAL CHEMISTRY
BIO CHEMISTRY
INDUSTRIAL AND APPLIED CHEMISTRY
NUCLEAR CHEMISTRY
ENVIRONMENTAL CHEMISTRY
POLYMERIC CHEMISTRY
PHYSICAL CHEMISTRY
It is the branch of chemistry that deals with the law and principle governing the
combinations of atoms and molecules in chemical reactions
ORGANIC CHEMISTRY
It is the branch of chemistry that deals with carbon compounds with the exception
of CO2, CO, metal carbonates, bicarbonates and carbides. Actually it is the
chemistry of hydrocarbons and their derivatives most of the consumers products
are organic in nature.
INORGANIC CHEMISTRY
It is the branch of chemistry that deals with the chemistry of elements and there
compounds, generally obtained from non-living organisms i.e. e. from minerals.
ANALYTICAL CHEMISTRY
It is the branch of chemistry of that deals with the study of methods and
techniques involve determining the kind, quality and quantity of various
component in a given substance.
BIO CHEMISTRY
1
It is the branch of chemistry that deals with the compounds living organisms I. e.
plants and animals and there metabolism in the living body.
INDUSTRIAL CHEMISTRY
It is the branch of chemistry that deals with the study of different chemical
processes involved in the chemical industries for the manufacture of synthetic
products like glass, cement, paper, soda ach, fertilizers, medicines etc.
NUCLEAR CHEMISTRY
It is the branch of chemistry that deals with the study of changes occurring in the
nuclei of atoms, accompanied by the emission of invisible radiations.
ENVIRONMENTAL
It is the branch of chemistry that deals with the study of the interaction of
chemical materials and their effect on the environment of animals and plants.
Personal hygiene, pollution and health hazards are important areas of
environmental chemistry.
POLYMERIC CHEMISTRY
It is the branch of chemistry that deals with the study of polymerization and the
products obtained through the process of polymerization such as plastics,
synthetic fibers, papers etc.
THE GREEK PERIOD
GREEK PHLOSPHERS LIKE PLATO
(347-428BC)
They thought that all matter was derived four elements earth, air, fire and water.
These elements have properties of there own such as hot dry cold and wet.
According to them, fire was hot and dry earth was dry and cold water was cold,
hot and wet and air was cold wet and hot.
THE MUSLIUM PERIOD
The Muslim period was from 600 to 1600AD.
JABIR IBNE-HAIYAN (721-803AD)
Jabir ibne-haiyan (721-803AD) generally known as the father of alchemy,
invented experimental methods for the preparation of nitric acid, hydrochloric
acid and white lead.
He also developed methods for the extraction of metals from their ores and
dyeing clothes.
AL-RAZI (862-930AD)
2
Al-razi (862-930AD) was a physician, alchemist and a philosopher. He was an
expert surgeon and was the first to use opium as an anesthesia. He divided the
substances into living and non-living origins, which was later adopted by
Berzelius, in 1608 to classify chemical compounds on the basic of their origins as
organic and inorganic compounds.
Al-razi prepared ethyl alcohol by the fermentation process.
AL-BERUNI (973-1048AD)
Al-beruni (97301048AD) contributed a lot in physics, metaphysics, mathematics,
geography and history. In the filed of chemistry. He determined the density of
different substances.
IBNE-SINA (980-1037AD)
Ibne-sina (980-1037AD) was famous for his contribution in the field of
medicines, medicinal chemistry, philosophy, mathematics and astronomy.
THE MODERN PERIOD
ROBERT BOYLE (1627-1691AD)
Robert Boyle (1627-1691AD) described affectionately as the father of modern
chemistry, was the first to put forward the idea that chemistry should be regarded
as systematic investigation of nature with the sole aim of promoting knowledge.
J. BLACK (1728-1799)
J. black (1728-1799) made a study of carbon dioxide.
J. PRIESLLY (1733-1804)
J. prieslly (1733-1804) discovered oxygen, sulphur dioxide and hydrogen
chloride.
SCHEELE (1742-1786)
Scheele (1742-1786) discovered chlorine.
CAVENDISH (1731-1810)
Cavendish (1731-1810) discovered hydrogen.
LAVOISIOR (1743-1794)
Lavoisior (1743-1794) discovered that oxygen constituted about one-fifth of air.
JHON DALTON (1766-1844)
3
John Dalton (1766-1844) made a great stride in chemistry with his atomic theory
of matter. The idea of atoms and molecules become the established fact and the
concept of atomic weight was also given by john Dalton.
GAY-LUSSAC (1778-1850)
AVOGADRO (1776-1856)
DULANG (1785-1838)
PETIT (1741-1820)
Petit (1741-1820) determination of relative atomic and molecular masses of
many substances.
MEANWHILE J. J. BERZELLIUS (1779-1848)
Meanwhile j. j. Berzelius (1779-1848) introduced the idea of symbols, formula
and chemical equation to make the study more systematic. This was further
enhanced.
MENDELEEFF (1824-1907)
Mendeleeff (1824-1907) who discovered the periodic arrangement of the
elements. The ionic theory and the law of electrolysis were put forward.
ARRHENIUS (1859-1927)
M. FARADAY (1791-1867)
M. faraday (1791-1867) respectively the work of.
J. J. THOMSON (1856-1940)
H. BECQUEREL (1852-1908)
M. CURIE (1867-1934)
NEIL BOHR (1885-1962)
E. RUTHERFORD (1891-1937)
E. Rutherford (1891-1937) led to the discoveries of structure of atom,
radioactivity, there by opening the door of the present nuclear age.
CHEMISTRY AND SOCIETY
4
There are three significant reasons to study chemistry. First chemistry has
important practical application in the society. The development of life saving
drugs in one and a complete list would touch upon most areas of modern
technology. Second chemistry is an intellectual enterprise, a way of explaining
our material world. Finally chemistry figures prominently in other fields, such as a
biology in the advancement of medicines. Chemistry in every field is a useful
intellectual tool for making important decisions.
THE SCIENTIFIC APPROACH IN CHEMISTRY
OBSERVATION, HYPOTHESIS, THEORY AND LAW
Over the years science has developed through a series of discoveries which
started off as observed natural phenomenon which had to be explained. This was
done by using scientific method in a systematic manner.
OSERVATION
Observation is a basic tool to go forth for elaborating a phenomenon but it may
vary from person to person according to his own skill of elaboration. Observation
of a thing is one of the scientific approaches in chemistry.
HYPOTHESIS
This explanation; which is still only a trial idea is called hypothesis. It may or may
not undergo a change as result further investigations and accumulation of more
knowledge for facts.
THEORY
When the hypothesis is supported by a large amount of different types of
observation and experiments, then it becomes a theory i.e. scientifically
acceptable idea or principle to explain a phenomenon.
SCIENTIFIC LAW
A theory which is tested again and found to fit the facts and from which valid
predictions may be made is then known as scientific law or principle.
FILL IN THE BLANKS
1. The early Greeks believed that every thing in the universe was made up of
four element earth, air, fire and water.
2. Al-razi divided chemical substances on the basic of their living and nonliving.
3. Organic chemistry is the branch of chemistry which deals with the carbon
compounds.
4. Bio chemistry is the backbone of living organism
5
5.
6.
7.
8.
PVC which is a plastic is the short name for poly vinyl chloride.
Oxygen was discovered by lavoisior.
The best disinfectant is scientific law.
The periodic arrangement was the result of mendeleeff work.
CHAPTER 2
CHEMICAL COMBINATION
LAW OF CHEMICAL COMBINATION
Chemistry deals with the matter and the change occurring in it chemists are
particularly interested in these changes where one or more substances are
changed in to quite different substances. They had found that these chemical
changes are governed by some empirical law known as law of chemical
combination.
The laws of chemical combination are following.
1. The law of conservation of mass.
2. The law of constant composition or
The law of definte proportion.
3. The law of multiple proportion.
4. The law of reciprocal proportion.
THE LAW OF CONSERVATION OF MASS
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 the product.
THE LAW OF CONSTANT COMPOSITION OR
THE LAW OF DEFINTE PROPORTION
Different samples of the same compound always contain the same element
combined together in the same proportional by mass.
THE LAW OF MULTIPLE PROPORTION
If to element combine to from more that one compound. The masses of element
that combine with a fixed mass of the other element are in the ratio of small
whole number or simple multiple ratio
FOR EXAMPLE.
Carbon (C) forms two stable compounds with oxygen (O) namely carbon
monoxide (CO) and carbon dioxide (CO2).
6
Compound
Carbon monoxide(CO)
Carbon dioxide (CO2)
Mass of carbon
(C)
12
12
Mass of oxygen
(O)
16
32
Ratio of oxygen
(O)
1
2
The different masses of oxygen 16 and 32 which combine with the fixed mass of
c (12g) are in the ratio of [16:32], i.e. 1:2, which is simple whole number ratio and
obeys. The law of multiple proportion.
THE LAW OF RECIPROCAL PROPORTION
When two different elements separately combine with the fixed mass of third
element. The proportion in which they combine with one an other shall either it’s
the same ratio or same multiple of it. This law was proposed by ritcher in 1972.
EXAMPLE
When two elements C and O separately combine with H to from methane (CH)
and water (H O) respectively it is very clear, that in methane 3g of C combine
with 1g of hydrogen and in water (H O) 8g of O combine with the same (fixed)
mass i.e. (1g) of H now when C and O combine with each other to form carbon
dioxide (CO), they do so in the same proportion i.e. 12:32 = 3:8 parts by mass.
CO
12:32
i.e. 3:8
PRACTICAL VERIFICATION
Landolt took the H-shaped tube and filled the two limbs ‘A’ and ‘B’ with silver
nitrate (AgNO3) in limbs ‘A’ and hydrochloric Acid (HCL) in limb ‘B’. The tube was
weight initially in a vertical position so that the solution should not inter wise after
sealing the tube. The reactants were mixed by interring and shaking the tube.
The tube was weighed after mixing the solution and the formation of white
precipitate of silver chloride (Agcl). He observe the weight remain some
AgNO3 + Hcl
Agcl + HNO3
7
BERZELLIUS EXPERIMENT
J.J. Berzelius (1779-1848) Berzelius heated log of lead (Pb) with various
amounts of sulpher (S). He got exactly 11.56g of lead sulphide and the excess of
sulpher was over when he used 18g of lead (Pb) with 1.56g of sulpher (S) he got
exact 11.56g of lead sulphide (Pbs) and the 8g of lead (Pb) remained un used.
8
Q1. Empirical formula C4H4 and the molecular mass 104 find n (C = 12, H = 1)
Data:
Empirical formula = CH
Molecular mass = 104
n
=?
As we know that
n = M.mass
.
E. Formula
Emperical formula C4H4
E. F of mass = 12 × 4 + 1 × 4
= 48 + 4
²
= 52
104
52
n=2
Ans.
Q2. Empirical formula C2H2O2 and the molecular mass 104 find n
(C = 12, H = 1, O = 16)
Data:
Empirical formula = CHO
Molecular mass = 104
n
=?
As we know that
n = Molecular Mass
Empirical formula
Empirical formula C2H2O2
Empirical formula of mass = 12 × 2 + 1 × 2 + 16 × 2
= 24 + 2 + 32
9
=
58
104
58
n=
1.79
Ans.
Q3. 50 gram Na & H2O number of moles.
Data:
Na = 23 a. m. u.
Given mass = 50 gm
n
=?
As we know that
Number of moles = given mass of substances
Atomic mass or formula mass
n = 50
23
n = 2.17
moles
Ans.
Data:
HO = 18 a. m. u.
Given mass = 50 gm
n
=?
As we know that
Number of moles = given mass of substances
Atomic mass or formula mass
n
= 50
18
n = 2.77
moles
Ans.
Q4. 28 gram CO2 & C6H6 number of moles.
10
Data:
CO2 = 44 a. m. u.
Given mass = 28
n
=?
As we know that
Number of moles = given mass of substances
Atomic mass or formula mass
n = 28
44
n = 0.63
moles
Ans.
Data:
C6H6 = 78
Given mass = 28
n
=?
As we know that
Number of moles = given mass of substances
Atomic mass or formula mass
n = 28
78
n = 0.35
moles
Ans.
Q5. 26 gram Al & CH4 number of moles (Al = 27)
Data:
Al = 27
Given mass = 26
n =?
As we know that
Number of moles = given mass of substances
Atomic mass or formula mass
n = 26
27
n = 0.96
moles
Ans.
Data:
CH4 = 16
11
Given mass = 26
n
=?
As we know that
Number of moles = given mass of substances
Atomic mass or formula mass
n
= 26
16
n = 1.62
moles
Ans.
ATOMIC MASS
Atomic mass is the average mass of naturally occurring isotopes which is
compared to the mass of one atom of carbon – 12 a. m. u.
ATOMIC MASS UNIT
Atomic mass unit is defined as one-twelfth the mass of C-12 atom (the carbon
atom that contains six protons and six neutrons).
EMPERICAL FORMULA
An empirical formula is simplest ratio of the atoms in a compound.
EXAMPLE
The molecular formula of benzene is C6H6. The ratio of carbon and hydrogen is
6:6 or 1:1. The empirical formula of benzene is CH.
MOLECULAR FORMULA
Molecular formula of an element or a compound shows the actual number of
atoms present in the molecule of these substances.
EXAMPLE
Compounds
Caron dioxide
Sugar
Glucose
Hydrogen peroxide
molecular formula
CO2
C12H22O11
C6H12O6
H2O2
A molecular formula may be a simple whole number multiple of an empirical
formula.
Molecular formula = (Empirical formula)
12
n
= Molecular formula
Empirical formula
MOLECULAR FORMULA MASS OR MOLECULAR MASS
The sum of atomic masses of all atom present in the molecular formula of a
substance or molecular is called molecular formula mass or molecular mass.
EXAMPLE
The atomic mass of carbon is 12 a. m. u. and oxygen is 16.
C = 1 × 12 = 12 a. m. u.
O = 2 × 16 = 32 a. m. u.
Molecular formula mass of CO2 = 44 a. m. u.
FORMULA MASS
The sum of atomic masses of atom in formula unit of substance is called formula
mass.
EXAMPLE
The atomic mass of sodium Na is 23 a. m. u. and the atomic mass of chlorine
35.5 a.m.u.
Sodium = Na = 1 × 23 = 23 a. m. u.
Chlorine = Cl = 1 × 35.5 = 35.5 a. m. u.
Formula mass of NaCl is
= 58.5 a. m. u.
MOLAR MASS
The relative molecular mass of a substance expressed in gram is called as molar
mass. It has fixed unit.
EXAMPLE
Molecular mass of carbon is 12 a. m. u. and therefore the molar mass of carbon
would be 12.g.
MOLE
The atomic mass, molecular mass and formula mass of a substance expressed
in gram is called mole.
EXAMPLE
One moles of carbon (C) = 12g
One moles of magnesium (mg) = 24g
One moles of water (H2O) = 18g
The number of moles can be calculated by following formula.
13
Number of moles = given mass of substance
.
Atomic mass or M. mass or F. mass
AVAGADRO’S NUMBER
The number of particles, atoms, ions molecules in one mole of a substance is
called Avogadro’s number. It denoted by ‘‘NA’’ its value is 6.02×10²³.
EXAMPLE
One mole of carbon (C) = 12g = 6.02×10²³ atoms
One mole of magnesium (mg) = 24g = 6.02×10²³ atoms
One mole of water (H2O) = 18g = 6.02×10²³ atoms.
Q1. Calculate the number of molecules in 9g of CO2.
Data:
Number of molecules?
Mass of substance = 9g
Molecular mass of CO2 44
As we know that
no of molecules = NA × mass of substance
Atomic mass
no of molecules = 6.02 × 10²³ × 9
44
no of molecules = 54.18 × 10²³
44
No of molecules = 1.231 ×
10²³
Ans.
Q2. Calculate the mass of one atom of carbon in gram.
Data:
According to Avogadro number.
14
C = 12g
6.02 × 10²³ atomic of C = 12
As we know that
1 atom of c = given mass
NA
= 12
6.02 × 10²³
1 atom of C =
2.993gm
Ans.
Q3. Calculate the mass of one molecule of water (H2O) in gram.
Data:
According to Avogadro number.
H O = 18gm
1 molecule of H2O = 18 = 6.02 × 10²³
As we know that
1 molecule of H O = given mass
NA
=
18 .
6.02 × 10²³
1 molecule of H O =
2.99gm
Ans.
Q4. Calculate the number of molecules in 6gm of CO2.
15
Data:
Number of molecule =?
Mass of substance = 6gm
Molecular mass of CO2 = 44
As we know that
Number of molecules = NA mass of substance
Atomic mass
Number of molecules = 6.02 × 10²³ × 6
44
Number of molecules = 36.14 × 10²³
44
Number of molecules =
0.82
Ans.
CHEMICAL CHANGE
Any change which alters the composition of a substance is called chemical
change.
FOR EXAMPLE
Rusting of iron is a chemical change.
CHEMICAL REACTION
The process of change in the composition of one or substance in which one pr
more new substance are formed with the result of chemical change called
chemical reaction.
TYPES OF CHEMICAL REACTIONS
The important types of chemical reactions are following.
1. Decomposition reaction
2. Addition reaction or synthesis
3. Single displacement reaction
4. Double displacement reaction
5. Combustion reaction
6. Neutralization
7. Hydrolysis
16
DECOMPOSITIOM REACTION
A reaction in which a chemical substance breaks down to from two or more
simple substance is called decomposition reaction.
EXAMPLE
Calcium carbonate decomposes into calcium oxide and carbon dioxide on
heating
CaCO3 (s)
heat
Cao (s) + CO2 (g)
Zinc nitrate decomposes in zinc oxide, nitrogen per oxide and oxygen on heating.
2Zn (Na3)2 (s) heat
2Zno (s) + 4NO2 (g)
ADDITION REACTION OR COMBINATION REACTION
OR SYNTHESIS
A chemical process of the composition of two or more substance in the from of a
single substance in called addition reaction, combination reaction or synthesis.
EXAMPLE
Calcium oxide react with carbon dioxide to from calcium carbonate.
CaO (s) + CO2 (g) heat
CaCO3 (s)
SINGLE DISPLACEMENT REACTION
A chemical reaction in which an atom or group of atom is replaced by another
atom or group of atom is called single displacement reaction.
EXAMPLE
Zinc replaces hydrogen in hydrogen chloride (HCl) to give zinc chloride.
Zn (s) + HCl (aq)
ZnCl2 (s) +H2 (g)
17
DOUBLE DISPLACEMENT REACTION
A chemical process in which two compounds exchange their partners or group of
atom, so that new compounds are formed called double displacement reaction.
EXAMPLE
When sodium hydroxide reacts with nitric acid (HNO3) they exchange their
partners to from sodium nitric and water.
NaOH (aq) + HNO3 (aq)
NaNO3 (s) + H2O (l)
CUMBUSTION REACTION
A reaction in which substance react with either free oxygen or oxygen of air, with
the rapid release of heat and flame is called combustion reaction.
EXAMPLE
When sulpher burn in air to forms sulpher dioxide.
S (s) + O2
SO2 (g)
NEUTRALIZATION
A chemical reaction of an acid with a base which gives a salt and water is called
neutralization.
EXAMPLE
When nitric acid react potassium hydroxide then potassium nitrate and water are
formed
HNO3 (aq) + KOH (aq)
KNO3 (aq) + H2O (l)
HYDROLYSIS
A chemical reaction of an acid and base which gives its constituents acid and
base called hydrolysis.
EXAMPLE
18
When sodium carbonate reacts with water it forms sodium hydroxide and
carbonic acid.
Na2CO3(s) + 2H2O (l)
2NaOH (aq) + H2CO3 (aq)
BALANCING EQUATION
1. C + O2
CO
REACTANTS
C (2)
PRODUCTS
C (2)
O (2)
O (2)
BALANCING EQUATION
2C + O2
2CO
2. CO + O2
CO2
19
REACTANTS
C (2)
PRODUCTS
C (2)
O (4)
O (4)
BALANCING EQUATION
2CO + O2
2CO2
3. KNO3
KNO2 + O2
REACTANTS
K (2)
PRODUCTS
K (2)
N (2)
N (2)
O (6)
O (6)
BALANCING EQUATION
2KNO3
O2
4. NaHCO3
2KNO2 +
Na2CO3 + H2O + CO2
REACTANTS
Na (2)
H (2)
C (2)
O (6)
PRODUCTS
Na (2)
H (2)
C (2)
O (6)
BALANCING EQUATION
2NaHCO3
CO2
5. CaCO3 + HCl
Na2 CO3 + H2O +
CaCl2 + H2O + CO2
20
REACTANTS
Ca (1)
C (1)
O (3)
H (2)
Cl (2)
PRODUCTS
Ca (1)
C (1)
O (3)
H (2)
Cl (2)
BALANCING EQUATION
CaCO3 + 2HCl
CO2
6. NH3 + O2
CaCl2 + H2O +
NO + H2O
REACTANTS
N (4)
H (12)
O (10)
PRODUCTS
N (4)
H (12)
O (10)
BALANCING EQUATION
4NH3 + 5O2
+6HO2
4NO
CHEMICAL EQUATION
A chemical equation is a short hand way of representing a chemical reaction.
Following steps are taken in writing a chemical equation.
1. Reactants are written on the left hand side of chemical equation while
products are written on the right.
2. Reactant and product are connected by an arrow.
3. Balance the equation .balance equation have the same kind and number
of atoms on each side.
4. Indicate physical state of the reactants and product we use (s) for solid, (l)
for liquid, (g) for gas and (aq) for aqueous.
BALANCING EQUATION
21
Most chemical equations can be balancing by inspection method, that is, by trial
and error method, with the experience, you should be able to balance any
equation quickly. In general we can balance the equation by the following steps.
1. Write correct formula for the reactant on the left and for the product on the
right with on arrow between.
2. Put a plus sing between them if two or more reactants or products are
present.
3. Count the number of atom of each element in the reactants and products.
4. Balance one element at a time using coefficient.
5. Check the coefficient. They most being their lowest possible ratios.
EXAMPLE OF BALANCING EQUATION
When hydrogen and oxygen react, the product is water. We write balance
equation fro the reaction. Reactants and products are know we can write a
skeleton equation
H2 (g) + O2 (g)
H2O (l)
KNO3
KNO3 + O2
REACTANTS
K (2)
PRODUCTS
K (2)
N (2)
N (2)
O (6)
O (6)
BALANCING EQUATION
2KNO3
O2
2KNO2 +
DENSITY
The mass of a substance per unit volume is called density. Its unit is kilogram per
cubic meter (kgm ³).
FORMULA
Density = mass
Volume
ATOM
The smallest particle of an element which represents the properties of the
element is called atom.
22
PHYSICAL PROPERTIES
1. Properties of a substance which
do not deals with its ability to
undergo chemical change are
called physical change.
2. They are related to the physical
state of matter.
3. These properties are the
characteristics of a substance.
CHEMICAL PROPERTIES
1. Processes of a substance which
indicate its ability to undergo
chemical change are called
chemical properties.
2. The are related to the chemical
change of substance.
3. These properties explain the
chemical behavior of a
substance.
FILL IN THE BLANKS
1. 18 gram of H2O contains 6.02 ×10²³ molecules.
2. A change which alters the composition of a substance is called chemical
change.
3. A reaction, in which a chemical substance breaks down to form two or
more similar substance, is called decomposition reaction.
4. The reaction of NaCl with AgNO3 is givens as
NaCl (aq) + AgNO3 (aq)
AgCl (s) NaNO3 (aq)
Is the reaction of the type double displacement reaction.
5. Addition reaction is the reaction in which two or more substances combine
together to form a single substance.
6. A reaction in which a substance burns in oxygen to produce heat and
flame is called combustion reaction.
7. Chemical reaction is the short hand method to describing a chemical
reaction.
8. The reaction Zn + 2HCl
ZnCl2 + H2 (g) is the single displacement
reaction.
9. When metals react with acids or water then produce hydrogen gas.
TICK THE CORRECT ANSWER
1. Mass is neither created nor destroyed during a chemical change, is the
statement of: law if conservation of mass.
a: Law of conservation of mass.
b: Law of definite proportion.
c: L aw of multiple proportion.
d: Law of reciprocal proportion.
23
1. A given compound always contains exactly the same proportion of
element, by mass, is the statement of: law of definite proportion.
a: Law of conservation of mass.
b: Law of definite proportion.
c: L aw of multiple proportion.
d: Law of reciprocal proportion.
2. The average mass of natural mixture of isotopes, which is compared to
the of one atom of C-12 a. m. u, is called: atomic mass.
a: Atomic mass
b: Mass number
c: Atomic number d: None of these
3. A formula that gives only the relative number of each type of atom in a
molecular is called: empirical formula.
a: Empirical formula
b: Molecular formula
c: Molecular mass
d: Formula mass
4. A formula that indicates actual number and type of atoms in a molecule is
called:
molecular formula
a: Empirical formula
b: Molecular formula
c: Molecular mass
d: Formula mass
5. The sum of atomic masses of all atoms in a molecule is called: molecular
mass.
a: Empirical formula
b: Molecular formula
c: Molecular mass
d: Formula mass
7. The sum of atomic masses of all atoms in a formula unit of substance is
called:
Formula mass.
a: Empirical formula
b: Molecular formula
c: Molecular mass
d: Formula mass
8. The mass of (1) mole of substance expressed in grams is called: molar
mass.
a: Empirical formula
b: Molecular formula
c: Molecular mass
d: Molar mass
9. 44 a. m. u. of CO2 is equal to molecular mass.
a: Molar mass
b: Atomic mass
c: Molecular mass
d: Mass number
10. 5 moles of H2O are equal to 90gm.
24
a: 80g
c: 100g
b: 90g
d: 90 a.m. u.
25