Fundamentals of Chemistry Notes 2023

What exactly is science?
Science is the systematic body of knowledge gathered via observations and experimentation.
Explanation
Our five senses acquire information about the material cosmos, which forms knowledge.
When the authenticity and veracity of facts are proved through experiments, however, this is referred to as science.
Example:
Water freezes at 0 degrees Celsius and boils at 1000 degrees Celsius.
When hydrogen and oxygen are joined chemically in a defined ratio, water is produced.
What is chemistry?
Chemistry is the discipline of science concerned with the study of matter, its composition, structure, properties, and reactions.
Chemistry is essential to many facets of existence.

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Origin of Chemistry
The origin of the term chemistry is the word KEEM. The same name was given to ancient Egypt. As time progressed, the science of chemistry spread from one generation to the next and eventually reached Arabia. There, the name KEEM was changed to AL KIMIYA.
The primary objective of chemistry is to understand the properties and transformations of matter. Chemistry is essential to our daily lives.
Simply stated, chemistry is the study of matter.
Branches of Chemistry with Examples
Following are the different branches of chemistry
Organic chemistry
“Organic chemistry is the discipline of science that studies molecules containing carbon.”
The majority of items we encounter on a daily basis are organic in origin. e.g.

• The majority of the food we eat is organic in nature.
• We wear organic clothing, such as cotton, silk, wool, etc.
• Coal, natural gas, and petroleum products are organic.
• Fuels that power our automobiles and businesses, such as gasoline, diesel, compressed natural gas (CNG), and coal gas
• Both allopathy and homoeopathy utilise chemical molecules. such as Penicillin and streptomycin
Other organic compound applications
• Insecticides such as DDT • Hormones & Steroids • Vitamins & Enzymes • Pigments & Dyes • Paper & Inks • Perfumes & Flavors • Plastic & Rubber • Explosives • Soap & Detergents • Herbicides such as Treflan • Photographic films & develops etc.
Carbon compounds with few exceptions
The following are exceptions:
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
- Carbon disulphide (CS2)
- Carbonates (CO32-)
- Bicarbonates (HCO3-)
- Cyanides (CN-)
- Cyanates (CNO -)
- Metal Carbides (C4-) etc.
Inorganic Chemistry
“Inorganic science is the discipline of chemistry that studies all elements and their compounds with the exception of organic compounds.”
Illustrations of inorganic compounds

Other applications of inorganic compounds include glass, washing soda (Na2CO3.10H2O), ceramics, etc.
Analytical Chemistry
Analytical chemistry is the discipline of chemistry that focuses on the procedures and tools used to determine the composition of matter.

To check

Biochemistry
Biochemistry is the branch of chemistry concerned with the physical and chemical processes that occur in living organisms.

For Example:
In the presence of chlorophyll and sunlight, photosynthesis produces glucose and oxygen from CO2 and H2O. Since photosynthesis is a chemical process that plants undergo.

Biochemistry is also the study of chemical reactions that occur within the human body.

Industrial Chemistry
Industrial chemistry is the subfield of chemistry that focuses on the methodologies and application of technology in the mass production of valuable compounds.

Massive manufacturing of any substance
The technique developed by Haber turns vast volumes of hydrogen and nitrogen into ammonia.

Nuclear chemistry
“Nuclear chemistry is the branch of chemistry that deals with the changes that occur in atomic nuclei.”

Example:
The study of the consequences of radioactive radiation or nuclear changes.
For instance, when alpha particles hit a nitrogen-14 atom and a proton is emitted, the process is represented as follows:

The processes of nuclear fission and fusion can be explained by nuclear chemistry
Environmental Chemistry
Environmental chemistry is the branch of chemistry concerned with chemicals and harmful compounds that contaminate the environment and their negative impact on humans.

Examples 1
Plantation aids in the mitigation of the greenhouse impact.

Examples 2
Compounds containing chlorofluorocarbons are responsible for the depletion of the ozone layer.
Since ozone layer depletion is an environmental issue.
Examples 3

Physical Chemistry
Physical chemistry is the discipline of chemistry concerned with the principles and theories necessary to comprehend the structure and transformations of matter.

OR
Physical Chemistry is the study of the concepts and principles that help us to grasp the structure and transformations of matter.
EXAMPLE
When heated, water evaporates and transforms into vapours. This phenomenon is explained by means of physical chemistry
Differentiate between the Branches of Chemistry
Vinegar contains 5% acetic acid. Acetic acid (CH3COOH) is an odourless, colourless liquid with a vinegar-like odour. It is used as a flavouring agent. Various forms of research on this substance can help you distinguish between different disciplines of chemistry.

Physical chemistry explains its transformation into a gaseous or solid state and applies laws and theories to comprehend its structure.

Since it is a carbon-containing substance, organic chemistry is the study of its chemical characteristics and technique of manufacture.

Examine its component parts. C, H, and O constitute inorganic chemistry.

Biochemistry is the study of the chemical interactions that acetic acid undergoes in the human body.




Dalton’s atomic theory
In 1803, English chemist John Dalton presented a theory on the nature and existence of matter
Basic postulates of dalton’s atomic theory
- Everything is composed of tiny indestructible particles called atoms
- Atoms of the same element have the same properties
- During chemical reactions, atoms combine in a simple ratio to form compounds
- Atoms can neither be created nor destroyed.
Basic Chemistry Definitions
What is meant by matter?
“Matter is everything that has mass and takes space.”

What is a substance?
Substance refers to the type of matter that has a particular composition and specific characteristics.
Or
A substance is any type of matter that possesses a unique set of characteristics different from those of another type of matter.


A substance may be in solid, liquid or gaseous form.
Examples of Substances
- Water
- Carbon dioxide
- Oxygen, Hydrogen, Common salt etc.
Types of Substances
1. Pure Substance
2. Impure Substance

What is an element?

An element is a pure substance that cannot be broken down into smaller substances. Each element’s atoms include the same atoms, which have identical structural and chemical properties.
There are 118 naturally occurring elements, of which 92 are found in nature and the remainder are created in laboratories.
An element is represented by a symbol

Atoms are the smallest particles of elements.

Elements have uniform composition throughout.
Element Examples
Sodium ( Na )
Magnesium ( Mg )
Oxygen ( O )
Argon ( Ar )
Some elements are represented by their Latin names e.g
- Copper Cuprum Cu
- Silver Argentum Ag
- Tin Stannum Sn
An element may be in solid, liquid or gas form.

Compound
A compound is a pure substance composed of two or more elements kept together in a constant proportion by chemical bonds.

Compounds are formed by the chemical combination of elements whose properties are entirely distinct from those of their parent elements. As a compound is a pure substance, its constituents cannot be separated through physical means.
The most essential property of a compound is its constant mass ratio. Hydrogen Peroxide [H2O2] is an example of a compound. Which is applied to the skin as an antiseptic to prevent infection from minor cuts? In hydrogen peroxide, the ratio of hydrogen to oxygen is always 2:2. Changing this ratio will yield an entirely different compound.
Compounds Characteristics
- The properties of compounds are different from the properties of the elements from which they are formed.
- A compound may be ionic or covalent
- Compounds have uniform composition throughout
- Millions of compounds exist in a universe
- Compounds are represented by chemical formulas
Additional Information
Note!!
Ionic bond
The complete transfer of an electron from one atom(metal) to another atom(non-metal)is called an ionic bond.


Covalent bond
A covalent bond is formed by the mutual sharing of electrons between the atoms.

Representation of compounds
The constituents of a compound are represented through a chemical formula. The formula shows the elements which chemically combined to form that particular compound.
Compound Examples
Hydrogen Peroxide H2O2
Water H2O
Methane [Natural Gas] CH4
What is a mixture?
A mixture contains two or more pure substances that retain their individual chemical properties.

A mixture is an impure substance.

A mixture is the physical mixing of two or more substances in any proportion. It is an impure material.
When two or more elements or compounds are mixed in any proportion such that their constituents retain their original properties, a mixture is produced. Various physical procedures, including distillation, filtration, and crystallisation, can be used to separate the contents of a mixture.
Components of a Mixture
A mixture consists of two constituents:
- Solute
- Solvent
Solute
Solute refers to the small component of a solution that is dissolved in the solvent.
Solvent
A solvent is the primary component of a solution that dissolves the solute. Also referred to as a dissolving media.
Examples of Mixture
Air is a mixture of oxygen, nitrogen, carbon dioxide, noble gases and water vapors.

A mixture of salt and water.

Soil is a mixture of sand,clay, mineral salt, water and air

A mixture of salt and sand.

Types of Mixture
2 types of mixture
- Homogeneous mixture
- Heterogeneous mixture
Homogeneous Mixture
A mixture that consists of only one phase is called a homogeneous mixture.
A homogeneous mixture has throughout the uniform composition
Examples of homogeneous mixture
- A mixture of salt and water.
- Air is a mixture of oxygen, nitrogen, carbon dioxide,
- Noble gases and water vapors.
Heterogeneous Mixture
A mixture consisting of two or more visible different components is called a heterogeneous mixture.
Heterogeneous mixtures do not have uniform composition
Examples of the heterogeneous mixture
- Oil floating on water.
- A mixture of salt and sand.
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For additional information
Bad breath may have certain advantages. Garlic’s chemical composition is highly complex. Garlic has around 200 chemical components. People who consume a lot of garlic have a reduced risk of stomach cancer, heart disease, and stroke compared to those who consume little or no garlic.
Difference between Compound and Mixture

What is an Atomic Number?

An atomic number is defined as the total number of protons present in the nucleus of an atom.
Atomic number ( Z ) = Number of Protons
Atomic Number Representation


Mass Number (A)
The mass number is defined as the total number of protons and neutrons in the nucleus of an atom.
Mass number ( A ) = Number of Protons + Number of Neutrons
The mass number is represented by the symbol A


Finding atomic number (Z) & Mass Number (A) of Oxygen atom?
Atomic number ( Z ) = Number of Protons
Mass number ( A ) = Number of Protons ( Z) + Number of Neutrons (n)
Atomic number (Z) & Mass Number (A) of Oxygen


Atomic Number (Z) = 8
No of protons= 8
Mass Number (A) = 16
No of protons= 8
+
No of neutrons = 8
How do you find the number of neutrons in an atom?
Atomic Number (Z) = 8
Mass Number (A) = 16
Number of neutrons ( n ) = Mass number ( A) – Atomic number (Z)
Number of neutrons ( n ) = 16 – 8
Number of neutrons ( n ) = 8
Determining the number of protons and neutrons in an atom
Question
The atomic number of an element is 17 and the mass number is 35. How many protons and
neutrons are present in the nucleus of an atom of this element?
Atomic number (Z) = 17 No of protons= 17
Mass Number ( A ) =35 No of protons + No of neutrons = 35

Number of neutrons ( n ) = 35 – 17
Number of neutrons ( n ) = 18

What is Relative atomic mass?
Relative atomic mass is defined as the mass of an atom of an element compared to the mass of a C-12 atom.
It is measured in either grams or amu. Consequently, the mass of one gram of an element represented in grams is known as the relative atomic mass.
Since an atom is an incredibly small particle, it is impossible to determine the precise mass of an element using a delicate balance. The chosen standard is carbon with a precise mass of 12g or 12amu.
Mass of one Carbon-12 atom=12amu
1 amu=mass of one C-12 atom/12
Now finding the relative atomic mass of hydrogen
8.4/100×12
=1.008 amu
EXAMPLE
One atom of sodium = 23 amu
One atom of chlorine = 35.5 amu
One atom of calcium = 40 amu
Why?
Comparing the mass of an atom of an element with the mass of a C-12 atom.
Reason
The mass of an atom in grams or kilograms is an extremely small value, so measuring such a small mass is not possible.
For that purpose atomic masses are expressed by comparing with the mass of C-12 (standard atom).
Nowadays, the atom chosen as the standard for comparison is the C-12.

we measure,
Mass = Kilogram
Length=meter
Temperature = Kelvin
Time = second

Why is it called Carbon-12?

Unit of Relative atomic mass
Atomic mass unit ( amu )
Definition
One atomic mass unit (amu) is defined as a mass exactly equal to one-twelfth the mass of one C-12 atom.
Mass of one C-12 atom = 12 amu
amu = mass of one C-12 atom / 12
Relative atomic masses of some elements.

AVERAGE ATOMIC MASS
The weighted average of atomic masses of naturally occurring isotopes of an element is known as average atomic mass.
EXPLANATION
In the majority of cases, the atomic mass of any element is rarely found to be in whole numbers. It is because most of the elements contain different isotopes and the relative atomic mass takes into account the natural abundance of each isotope.
Average Atomic Mass Formula
Average atomic mass = Atomic mass of 1st isotope × its % abundance/100 + Atomic mass of 2nd isotope × Its % abundance /100
Chemical Formula
The symbolic representation of a compound that shows elements in the compound and also the ratio of their atoms is called the chemical formula.


Chemical Formulas Examples
Calcium Carbonate = CaCO3
Water = H2O
Sulphuric acid = H2SO4
Benzene = C6H6
Types of Chemical Formulas
- Empirical Formula
- Molecular Formula
Empirical Formula
The chemical formula that gives the simplest or the most reduced whole number ratio of atoms present in a compound is called the empirical formula.


Empirical Formula of H2O2
The actual formula for hydrogen peroxide is H2O2 which shows that there is one hydrogen atom for every oxygen atom. Therefore the simplest ratio of hydrogen to oxygen is 1:1.So the empirical formula of hydrogen peroxide is HO.
Molecular Formula
The chemical formula that gives the actual number of atoms present in one molecule of a compound is called the molecular formula.
The molecular formula could be derived from the empirical formula in the following way i.e
Molecular formula = n(Empirical formula) where n could be equal to 1,2,3,4,5…
FOR EXAMPLE
The empirical formula of benzene is CH so its Molecular Formula could be derived in the following way i.e
The molecular formula of Benzene =n(CH)
Here the value of n = 6
So Molecular formula of benzene=C6H6

COMPOUND | EMPIRICAL FORMULA | MOLECULAR FORMULA |
GLUCOSE | CH2O | C6H12O6 |
ETHENE | CH2 | C2H4 |
Question
5% of vinegar is acetic acid. This molecule has 2 carbon, 4 hydrogen, and 2 oxygen atoms. Write its empirical and molecular formulas.
Given:
Number of carbon atoms = 2
Number of hydrogen atoms = 4
Number of oxygen atoms = 2
Find out its empirical and molecular formulas
Solution:
C: H: O
2: 4: 2


Empirical formula = CH2O
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Question
Caffeine ( C8H10 N4 O2) is found in tea and coffee. Write its empirical formula.
Given:
Molecular formula = C8H10 N4O2
Find out its empirical formula
Solution:

Empirical formula = C4H5 N2O
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Why do some compounds have the same empirical and molecular formula?
If the chemical formula cannot be further reduced, the empirical formula and molecular formula are same.

Molecular mass
Molecular mass is defined as “ the sum of atomic masses of all the atoms present in the molecule “.
To find the molecular mass of a compound, you have to add up the atomic masses of all the atoms
In the compound.
For Example
Molecular mass of H2O
=2(atomic mass of H) + atomic mass of O
=2 (1) + 16
=2 + 16
=18 amu
Molecular mass of NH3
NH3
=14 + 3 (1)
=14 +3
=17 amu
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Determine the molecular mass of glucose C6H12O6 which is also known as blood sugar.
Problem solving strategy
Multiply the atomic mass of carbon, hydrogen and oxygen by their subscripts and add.
SOLUTION
Molecular mass of C6H12O6 = 6(12.00) + 12(I.008) + 6(16.00)
= 180.096 amu
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Determine the molecular mass of naphthalene C10H8 which is used in mothballs
Problem solving strategy
Multiply the atomic mass of carbon, and hydrogen by their subscripts and add.
SOLUTION
Molecular mass of C10H8 = 10 (12 )+ 8 (1)
= 120 + 8
= 128 amu
Difference between Molar mass and Molecular mass

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Formula unit
The smallest repeating unit of an ionic compound which shows the simplest ratio between its ions is called the formula unit.
Example
The simplest ratio between Mg and Cl in the crystal lattice of MgCl is 1:1 hence the formula unit of magnesium chloride is MgCl.
ION
When an atom loses or gains an electron it becomes a charged particle known as an ion.

EXPLANATION
Most of the time, an atom is electrically neutral, but when it takes or loses an electron, it acquires a charge and becomes an ion.
Types of Ions
There are two types of ions
- Cation
- Anion

CATION
The charged specie that is formed by the loss of electrons is known as a cation.
The number of protons are greater than electrons in a cation
EXAMPLE
Mg+2 ,H+1
ANION
The charged specie that is formed by the gain of electrons is known as an anion.
the number of electrons are greater than protons in anions.e.g Cl-1,O-2


Formula Mass
The sum of atomic masses of all the atoms in the formula unit of a compound is called formula mass.

NaCl Formula mass
=23 + 35.5
=58.5 amu
The simplest ratio between cations & anions in an ionic compound is called formula unit.
Formula mass of C3H6O
= 12 x 3 + 1 x 6 + 16
= 36 + 6 + 16
= 58 amu
Formula mass of MgSO4
= 24 + 32 + 16 x 4
= 24 + 32 + 64
= 120 amu
Molecular Ion
When a molecule gains or loses electrons, the resulting species is called a molecular ion.

Molecular ions that contain a positive charge are formed by the loss of an electron from neutral molecules.
Molecular ions having a negative charge are formed by the gain of an electron from neutral molecules
Examples of molecular ions
Positive molecular ions
Positive molecular ions are known as molecular cations E.g
O2+ ,CH4+ , H3O+ , NH4+


Negative molecular ions
Negative molecular ions are known as molecular anions E.g
SO4-2, OH–
Free Radical
An atom or molecule having an unpaired electron in its valence shell is termed a free radical.
EXPLANATION
A free radical is formed by the homolytic fission of a molecule such that each atom in the molecule obtains an unpaired electron. A free radical has no charge and is represented by a [.] on the symbol of the element. It is a highly reactive specie and cannot exist independently.
Reaction involving free radicals
Cl2 → 2Cl.
The chlorine-free radical will react with methane CH4 to form methyl free radical.
CH4 + Cl.→ CH3. + HCl
Now the methyl free radical reacts with another Cl2 molecule to form chloromethane and chlorine free radical
CH3. + Cl2→CH3Cl + Cl.
The reaction goes on until the formation of a stable product.

Free Radical Representation

Free radical having odd no of valence electrons i.e. 1,3,5,7…..
How does free radical form?
In the presence of heat /light, homolytic breakage of the molecule occurs resulting in the formation of free radicals.

Free radicals have incomplete valence shell electrons. Due to this, they are unstable & short-lived.
What is mole in Chemistry?
Mole
A mole is the mass of a substance that includes 6.023 x 1023 of the substance’s particles. The mole is the SI unit used to measure substance amounts.
mol is its symbol. By definition One mole of carbon-12 weighs 12 grams and contains 6.022140857 x 1023 carbon atoms.
OR Relative atomic mass, Formula mass, and Molecular mass expressed in grams is called a mole.
Examples
1 Mole of Oxygen =16g=6.023×1023 atoms
1 Mole of NaCl =58.5g=6.023×1023 formula units
1 Mole of water =18g=6.023×1023 molecules
Avogadro’s number
The quantity of units contained in a mole of any material is known as Avogadro’s number or Avogadro’s constant. The value is 6.022140857×1023. In accordance with the characteristics of the reaction and the material, the units might be electrons, ions, atoms, or molecules.
Therefore, the value would be as follows if you wanted to know how many particles there are in 3 moles of a substance:
= 3 x 6.023 x 1023
= 1.81 x 1024 particles
REPRESENTATION
It is represented by NA
Molar mass
The mass of one mole of particles ( atoms , molecules or formula units) expressed in grams is called molar mass.



For Example:
Mass of I mole of C- atom (6.022 x 1023 atoms) = 12 g
Molar mass of carbon atom = 12 g/ mol
Mass of I mole of H2O molecule (6.022 x 1023 molecules) = 18g
Molar mass of water molecule = 18g / mol
Mass of I mole of NaCl formula unit (6.022 x 1023 formula units) = 58.5g
Molar mass of NaCl formula unit = 58.5g /mol
How to Calculate molar mass:
HCl
=1 + 35.5
=36.5 g/mol
Ca(OH)2
=40 + 2 (16) +2(1)
=40 +32 +2
=74 g/mol
NH3
=14 + 3 (1)
=14 +3
=17 g/mol
CO2
=12 + 2 (16)
=12 +32
=44 g/mol
NaCl
=23 + 35.5
=58.5 g/mol
The mass of 5 moles of element X is 60g. Calculate the molar mass of this element. Also name the element.
Given data:
Mole of element X = 5 mol
Mass of element X = 60g
Required:
Molar mass of element X = ?
Solution:
Using formula to find the molar mass :

Putting values in formula :
so

Thus the molar mass of element X is 12 g/mol
&
the element X is carbon.
Mole Problems Practice
How do you calculate moles from molar mass?
1st Method
A technician weighs 40g of Sodium chloride (NaCl) . How many moles of formula units are in a sample?
Given data:
Mass of NaCl = 40 g
Required:
Moles of NaCl formula units =?
Solution:
Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol
We know that:


2nd Method
A technician weighs 40g of Sodium chloride (NaCl) . How many moles of formula units are in a sample.
Given data:
Mass of NaCl = 40 g
Required:
Moles of NaCl formula units = ?
Solution:
Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol
We know that :
58.5 g NaCl = 1 mole of NaCl formula units
40 g NaCl = 40/58.5 mole of NaCl formula units
= 0.684 mol of NaCl formula units
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Gram Atomic Mass, Gram Molecular Mass and Gram Formula Mass

GRAM ATOMIC MASS
Gram atomic mass is the term used to describe an element’s atomic weight when stated in grams. An element’s molar mass is defined as the mass of one mole in grams.
EXAMPLE
Helium, for instance, has a gram atomic mass of 4 g . Similarly sodium (Na), has a gram atomic mass of 22.99 grams and an atomic weight of 22.99 u. A mole of sodium thus weighs 22.99 g of atoms.
GRAM FORMULA MASS
The formula mass of an ionic compound expressed in grams is called gram formula mass
It can be explained with the help of the following example
Formula mass of NaCl = 23 + 35.5
= 58.5amu
Therefore, the gram formula mass of NaCl = 58.5g = mole of NaCl formula units.
Formula mass of KCl = 39 + 35.5
= 74.5amu. So, gram formula mass of KCl = 74.5g
GRAM MOLECULAR MASS
The mass in grams of one mole of a molecule is known as the gram molecular mass. The molar mass and gram molecular mass are equivalent. The sole distinction is that the mass unit to be utilized is specified by gram molecular mass. The mass of a molecule can be expressed in either grams or grams per mole (g/mol).
EXAMPLES
Molecular mass of H2O = 2 x 1.008 + 16 = 18.016amu So, gram molecular mass of H2O = 18.016g Molecular mass of C6H12O6 = 6 x 12 + 12 x 1.008 + 16 x 6 = 180.096amu So, gram molecular mass of C6H12O6 = 180.096g.
Differentiate between gram atomic mass, gram molecular mass, and gram formula mass.
ANSWER
Statements
- In contrast to gram formula mass, which represents one mole of ionic formula units of a compound, gram atomic mass denotes one mole of atoms of an element. Gram molecular mass denotes one mole of molecules of a compound or an element that exists in a molecular state.
- Gram atomic mass contains 6.022 x 1023 atoms, gram molecular mass contains 6.022 x 1023 molecules whereas gram formula mass contains 6.022 x 1023 formula units
- Therefore one mole can be defined as formula mass, atomic mass, or molecular mass expressed in grams.
CHEMICAL CALCULATIONS
Fundamentals of Chemistry Problems Practice
Determine the molar masses of sodium, nitrogen, sucrose
Solution
Molar masses of sodium Na
1 mole of Na = 23g
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Nitrogen occurs as diatomic molecules.
Molar mass of Nitrogen N2
= 14 x 2
= 28amu
Therefore, mass of 1 mole of N2 = 28 g
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Molecular mass of Sucrose C12H22O11
= 12×12 + 1×22 + 16×11
= 144 + 22 + 176
Therefore, mass of 1 mole of sucrose = 342g
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2. Oxygen is converted to ozone O3 during thunderstorms. Determine the mass of ozone if 9.05 moles of ozone is formed in a storm.
Ozone is a molecular substance. Determine its molar mass and use it to convert moles to mass in grams.
9.05 moles of O3 ⎯⎯→ ? g of O3
Solution:
1 mole of O3 = 16 x 3 = 48 g
1 mole of O3 = 48 g
So, 9.05 moles of O3 = 48 g x 9.05
= 434.4g of O3
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3. When methane burns CO2 is formed is 0.25 moles of CO2 is formed what mass of CO2 is produced?
SOLUTION
Molar mass of CO2 = 12 + 16 x 2 = 44g
1 mole of CO2 = 44g of CO2
So, 0.25 moles of CO2 = 44 x 0.25 = 11g of CO2
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4. Calculate the moles of each of the following
A.Balloon filled with 5g of hydrogen
B.A block of ice that has a mass of 100g
SOLUTION
a) Molar mass of H2 = 1.008 x 2 = 2.016g
1 mole of H2 = 2.016g
So, 2.016g of H2 = 1 mole of H2
1g of H2 = 1/2.016 moles of H2
5 gram of H2 =1÷2.016×5
5 gram of H2 = 2.48 Moles of H2
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b.1 Mole Of H2O =2×1.008+16
1 Mole of H2O =2.016+16
1Mole of H2O=18.016g
So 1 gram of H2O = 1÷18.016 moles
100 Gram of H2O= 1÷18.016×100 moles
100 grams of H2O=5.55 Moles of H2O
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5. Zn Is a metal that is used to galvanize steel to prevent corrosion. How many atoms are there in 1.25moles of Zn?
SOLUTION
1 mole of Zn contains = 23 6.022 x 1023 atoms
1.25 moles of Zn contains = 6.022 x 1023 x 1.25 = 7.53 x 1023 Zn atoms
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6. Methane is one of the main components of natural gas . Calculate how many moles are in 0.5 moles of a pure sample of methane.
SOLUTION
1 mole of CH4 contains = 6.022 x 1023 molecules
So, 0.5 moles of CH4 will contain = 6.022 x 1023 x 0.5 = 3.011 x 1023 molecules
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7. Titanium is a metal that is used in rockets. Calculate the number of moles in a sample containing 3.011×1023atoms
SOLUTION
6.022 x 1023 atoms = 1 mole
3.011 x 1023Atoms→ ? mole
6.022×1023 atoms = 1 mole of Ti
1 Ti atom =1÷6.022×1023 moles of Ti
3.011×1023 Ti atoms = 1÷(6.022×1023)×3.011×1023 moles of Ti
=0.5 moles of Ti
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