Lesson-1-Introduction-to-Chemistry 2.pdf

Introducing the chemistry

1. INTRODUCTION TO
CHEMISTRY:
DEFINITION OF QUALITATIVE
CHEMISTRY
LESSON 1

2. INTRODUCTION
Qualitative chemistry involves identifyingand characterizing
the chemical components of a substance without measuring their
quantities.
This branch of chemistry focuses on understanding the presence
or absence of specific compounds, their chemical properties,
and their interactions.

3. IN FOOD TECHNOLOGY,
QUALITATIVE CHEMISTRY
PLAYS A CRUCIAL ROLE IN
SEVERAL WAYS:
1. Authenticity and
Classification: It helps in
verifying the authenticity of
food products by identifying
specific markers that indicate
the presence of genuine
ingredients.

4. IN FOOD TECHNOLOGY,
QUALITATIVE CHEMISTRY
PLAYS A CRUCIAL ROLE IN
SEVERAL WAYS:
2. Detection of
Contaminants: Qualitative
analysis is essential for
detecting impurities or
contaminants in food, ensuring
safety and compliance with
health standards.

5. IN FOOD TECHNOLOGY,
QUALITATIVE CHEMISTRY
PLAYS A CRUCIAL ROLE IN
SEVERAL WAYS:
3. Fraud Prevention: By
identifying fraudulent
substitutions or adulterations,
qualitative chemistry helps
maintain the integrity of food
products.

6. IN FOOD TECHNOLOGY,
QUALITATIVE CHEMISTRY
PLAYS A CRUCIAL ROLE IN
SEVERAL WAYS:
4. Quality Control: It aids in
monitoring the quality of food
during processing and storage
by identifying any chemical
changes that may affect the
product.

7. SCOPE OF
QUALITATIVE
CHEMISTRY
1. Analyzing Food Additives:
Purpose: Food additives are used to
enhance the flavor, color, texture, and
shelf life of food products.
Application: Qualitative chemistry
helps identify specific additives like
artificial sweeteners, colorants, and
emulsifiers. This ensures that only
approved additives are used and
that they are within safe limits. For
example, detecting artificial colorants
in candies ensures they comply with
food safety regulations.

8. SCOPE OF
QUALITATIVE
CHEMISTRY
2. Detecting Preservatives:
Purpose: Preservatives prevent spoilage
and extend the shelf life of food
products by inhibiting the growth of
microorganisms.
Application: Qualitative analysis can
detect common preservatives such as
benzoates, nitrates, and sulfites. This
ensures that the preservatives used are
safe for consumption and meet
regulatory standards. For instance,
detecting sulfites in dried fruits helps
prevent allergic reactions in sensitive
individuals.

9. SCOPE OF QUALITATIVE CHEMISTRY
Here are some common examples:
E200: Sorbic Acid -used to inhibit the growth of mold, yeast, and fungi in various foods.
E220: Sulphur Dioxide -commonly used in dried fruits, wines, and some juices to prevent spoilage and
discoloration.
E270: Lactic Acid -used in fermented foods like yogurt and pickles to maintain acidity and prevent spoilage.
E282: Calcium Propionate -used in baked goods to prevent mold growth.
E290: Carbon Dioxide -used in carbonated beverages to inhibit microbial growth.

10. SCOPE OF QUALITATIVE CHEMISTRY
In food technology,
preservatives are assigned
specific codes known as E
numbers to standardize and
identify them easily.
These codes are used across
Europe and other regions to
indicate approved food
additives.
E200to E299: This range is
designated for preservatives.
These substances help prevent
the growth of microbes,
extending the shelf life of food
products and ensuring they
remain safe to consume.

11. SCOPE OF QUALITATIVE CHEMISTRY
E200: Sorbic Acid -used to inhibit the growth of mold, yeast, and fungi.
E202: Potassium Sorbate -a salt of sorbic acid, used similarly to inhibit mold and yeast.
E210: Benzoic Acid -used in acidic foods like salad dressings and carbonated drinks.
E211: Sodium Benzoate -a salt of benzoic acid, used in acidic foods and beverages.
E220: Sulphur Dioxide -used in dried fruits, wines, and some juices to prevent spoilage and discoloration.
E223: Sodium Metabisulphite -used in wines and dried fruits to prevent oxidation and spoilage.
E224: Potassium Metabisulphite -similar to sodium metabisulphite, used in wines and dried fruits.
E226: Calcium Sulphite-used as a preservative in some canned vegetables.

12. SCOPE OF QUALITATIVE CHEMISTRY
E252: Potassium Nitrate -used in cured meats and some cheeses.
E260: Acetic Acid -used in pickling and as a preservative in sauces.
E270: Lactic Acid -used in fermented foods like yogurt and pickles.
E280: Propionic Acid -used in baked goods to prevent mold growth.
E282: Calcium Propionate -used in bread and other baked goods to prevent mold.
E290: Carbon Dioxide -used in carbonated beverages to inhibit microbial growth.
E296: Malic Acid -used as a preservative and acidity regulator in various food products.
E297: Fumaric Acid -used as a preservative and acidity regulator, often found in baking powders and beverages.

13. SCOPE OF
QUALITATIVE
CHEMISTRY
3. Identifying Contaminants:
Purpose: Contaminants can enter food
through environmental exposure,
processing, or packaging, posing health
risks.
Application: Qualitative chemistry is
crucial for detecting harmful substances
like heavy metals (e.g., lead, mercury),
pesticides, and other toxic compounds.
This ensures that food products are safe
for consumption. For example, detecting
pesticide residues in vegetables ensures
they are within permissible limits.

14. SCOPE OF
QUALITATIVE
CHEMISTRY
4. Flavor and Aroma Analysis:
Purpose: The flavor and aroma of
food products are key factors in
consumer acceptance and preference.
Application: Qualitative chemistry
helps identify volatile compounds
responsible for flavorand aroma. This
is essential for developing new
flavors and ensuring consistency in
taste and smell. For instance,
identifying the compounds responsible
for the aroma of coffee helps
maintain its quality.

15. SCOPE OF
QUALITATIVE
CHEMISTRY
5. Nutrient Identification:
Purpose: Ensuring the presence of
essential nutrients in food products is
vital for consumer health and nutrition.
Application: Qualitative analysis
detects vitamins, minerals, and other
nutrients in food products. This ensures
that nutritional claims on labels are
accurate and helps in fortifying foods
with necessary nutrients. For example,
detecting vitamin C in fruit juices
ensures they meet nutritional
standards.

16. SCOPE OF
QUALITATIVE
CHEMISTRY
6. Allergen Detection:
Purpose: Identifying potential
allergensin food products is crucial
for consumer safety, especially for
individuals with food allergies.
Application: Qualitative chemistry can
detect trace amounts of allergens
such as peanuts, gluten, and dairy. This
helps prevent allergic reactions and
ensures proper labeling. For instance,
detecting gluten in supposedly gluten-
free products ensures they are safe
for individuals with celiac disease.

17. SCOPE OF
QUALITATIVE
CHEMISTRY
7. Monitoring Fermentation Processes:
Purpose: Fermentation is a key process
in producing products like yogurt, cheese,
and alcoholic beverages.
Application: Qualitative chemistry is
used to monitor the fermentation process
by identifying the microorganisms
involved and their metabolic by-
products. This ensures the desired
quality and safety of the final product.
For example, identifying lactic acid
bacteria in yogurt ensures proper
fermentation and product consistency.

18. FUNDAMENTAL
CONCEPTS
Concept of the Mole
Definition: A mole is defined as the
amount of a substance that contains
exactly 6.02214076×10^23
elementary entities (such as atoms,
molecules, ions, or electrons). This
number is known as Avogadro’s
constant.
Origin: The term “mole” was introduced
by the German chemist Wilhelm
Ostwald in the late 19th century,
derived from the Latin word “moles,”
meaning a heap or pile.

19. SIGNIFICANCE IN
CHEMISTRY
1. Quantifying Substances:
•The mole allows chemists to count
particles by weighing them. For
example, one mole of carbon-12 atoms
weighs exactly 12 grams and contains
6.02214076×10
23
atoms.
•This makes it easier to relate the mass of
a substance to the number of particles it
contains.

20. SIGNIFICANCE IN CHEMISTRY
2. Chemical Reactions:
The mole concept is crucial for understanding and balancing chemical equations. It
allows chemists to determine the proportions of reactants and products involved in a
reaction.
For example, in the reaction
2??????
2+�
2​→2??????
2�
two moles of hydrogen react with one mole of oxygen to produce two moles of water.

21. SIGNIFICANCE IN CHEMISTRY
3. Molar Mass:
The molar mass of a substance is the mass of one mole of that substance. It is
expressed in grams per mole (g/mol) and is numerically equal to the atomic or
molecular weight of the substance.
For instance, the molar mass of water (??????₂�) is approximately 18 g/mol, meaning one
mole of water weighs 18 grams.

22. SIGNIFICANCE IN CHEMISTRY
4. Concentration of Solutions:
The concept of molarity, which is the number of moles of solute per liter of solution, is
based on the mole. It is a key measure in preparing and analyzing solutions in
chemistry.
For example, a 1 M (molar) solution of sodium chloride (NaCl) contains one mole of
NaCl dissolved in one liter of water.

23. PRACTICAL
APPLICATIONS
Stoichiometry: The
mole is essential in
stoichiometry, which
involves calculating the
quantities of reactants
and products in
chemical reactions.

24. PRACTICAL
APPLICATIONS
Pharmaceuticals: In
drug formulation and
dosage calculations, the
mole helps in
determining the precise
amount of active
ingredients.

25. PRACTICAL
APPLICATIONS
Environmental
Science: The mole is
used to measure
pollutant
concentrations in air,
water, and soil.

26. ATOMIC STRUCTURE
Atoms
Atomsare the smallest units
of matter that have the
properties of an element.
Elements are substances that
cannot be broken down into
simpler substances by
chemical means.

27. ATOMIC STRUCTURE
Atomic Model
The atomic model is not a fixed
representation of reality, but a
simplified way of explaining the
observations and experiments of
scientists.
It is important to understand that
the atomic model is not the same
as the actual atom, but a useful
approximation that helps us
predict and explain the behavior
of atoms and molecules.

28. ATOMIC STRUCTURE
Structure of Atoms
1. Nucleus:
oProtons:
Charge: Positively charged
particles.
Mass: Approximately 1 atomic mass
unit (amu).
Location: Found in the nucleus at the
center of the atom.
Role: The number of protons (atomic
number) determines the element’s
identity. For example, hydrogen has
1 proton, while carbon has 6
protons.

29. ATOMIC STRUCTURE
Structure of Atoms
oNeutrons:
Charge: Neutral (no charge).
Mass: Slightly more than 1 amu, but
often considered approximately 1
amu.
Location: Also located in the nucleus.
Role: Neutrons contribute to the
mass of the atom and help stabilize
the nucleus. The number of neutrons
can vary in the same element,
leading to different isotopes.

30. ATOMIC STRUCTURE
Structure of Atoms
oProtons and Neutrons:
The number of protons in an atom determines its identity as an element.
This is called the atomic number.
The number of protons and neutronsin an atom determines its mass. This
is called the mass number.
For example, the atomic number of hydrogensis 1, which means it has 1
proton in its nucleus. The atomic number of carbonis 6, which means it has
6 protons in its nucleus.
The atomic number of an element is also equal to the number of electrons in
a neutral atom.

31. ATOMIC STRUCTURE
2. Electron Cloud:
oElectrons:
Charge: Negatively charged particles.
Mass: Negligible compared to protons
and neutrons (about 1/1836 of a
proton’s mass).
Location: Move in regions called
electron clouds or orbitals around the
nucleus.
Role: Electrons are involved in chemical
bonding and reactions. The
arrangement of electrons in different
energy levels or shells determines the
chemical properties of an element.

32. ATOMIC STRUCTURE
Atomic Structure Overview
Nucleus: The dense central core
of the atom, containing protons
and neutrons. It accounts for most
of the atom’s mass.
Electron Cloud: The region
surrounding the nucleus where
electrons are likely to be found.
This area is much larger than the
nucleus and defines the atom’s size.

33. ATOMIC STRUCTURE
Importance of Subatomic Particles
Protons: Define the element and its
position in the periodic table. The
number of protons equals the atomic
number.
Neutrons: Contribute to the atomic mass
and stability of the nucleus. Different
numbers of neutrons result in isotopes of
the same element.
Electrons: Determine the atom’s chemical
behavior and how it interacts with other
atoms. The arrangement of electrons in
shells and subshells influences bonding
and reactivity.

34. ATOMIC STRUCTURE
Example: Carbon Atom
Protons: 6
Neutrons: Typically, 6 (but
can vary in isotopes, e.g.,
Carbon-12, Carbon-14)
Electrons: 6, arranged in
two energy levels (2 in the
first shell, 4 in the second
shell)

35. BASIC BONDING
THEORIES
Chemical bond are the focus
that hold atoms together in
compounds. There are three
primary types of chemical
bonds: ionic, covalent, and
metallic. Each type of bond
has unique characteristics
and plays a crucial role in
various applications.,
including food chemistry.

36. BASIC BONDING
THEORIES
1. Ionic Bonds
Definition: Ionic bonds from when electrons
are transferred from one atom to another,
resulting in the formation of positively and
negatively charged ions. These oppositely
charged ions attract each other, creating a
strong bond.
Example in Food Chemistry: Table salt
(sodium chloride, NaCl) is a common
example. Sodium (Na) donates an electron
to chlorine (Cl), forming Na+ and Cl-ions
that bond together. Ionic bonds are also
found baking soda (sodium bicarbonate,
NaHCO3), which is used as a leavening
agent in baking.

38. BASIC BONDING
THEORIES
2. Covalent Bonds
Definition: Covalent bonds form when
atoms share pairs of electrons. This type
of bond typically occurs between
nonmetal atoms.
Example in Food Chemistry: Water
(H2O) is a classic example, where each
hydrogen atom shares an electron with
the oxygen atom, forming a stable
molecule. Another example is the bonds
in proteins, where amino acids are
linked by peptide bonds (a type of
covalent bond) to form longs chains.
These proteins are essential for the
structure and function of food products.

39. BASIC BONDING
THEORIES
3. Metallic Bonds
Definition: Metallic bonds occur when
electrons are shared among a lattice of
metal atoms. These delocalized electrons
allow metals to conduct electricity and
heat and provide malleability and
ductility.
Example in Food Chemistry: While
metallic bonds are less common in food
chemistry, they are crucial in the
equipment used for food processing. For
instance, stainless steel, which contains
metallic bonds, is widely used in kitchen
utensils and food processing machinery
due to its durability and resistance to
corrosion.

41. LAW OF CHEMICAL
EQUILIBRIUM
Chemical Equilibrium
Chemical equilibrium is the state in
a chemical reaction where the
concentrations of reactants and
products remain constant over time.
This occurs when the rate of the
forward reaction (reactants turning
into products) equals the rate of
the reverse reaction (products
turning back into reactants).

42. LAW OF CHEMICAL
EQUILIBRIUM
Law of Chemical Equilibrium
The Law of Chemical equilibrium
states that at equilibrium, the ratio
of the concentrations of the
products to the concentrations of
the reactants, each raised to the
power of their respective
coefficients in the balanced
chemical equation, is constant. This
constant is known as equilibrium
constant
Kc

43. LAW OF CHEMICAL EQUILIBRIUM
Consider an example of chemical equilibrium using the reaction
between nitrogen dioxide (��₂) and dinitrogen tetroxide
(�₂�₄), which is relevant in food packaging and preservation
due to its involvement in the formation of nitrogen-based
preservatives.
Example: ��₂and �₂�₄Equilibrium
Reaction:
2��
2??????�
2�
4(??????)

44. LAW OF CHEMICAL EQUILIBRIUM
2��
2??????�
2�
4(??????)
Step-by-Step Breakdown
1. Initial Setup:
Suppose we start with a certain amount of nitrogen dioxide
(��
2)in a sealed container.
Over time, ��
2molecules will react to form dinitrogen
tetroxide (�
2�
4), and �
2�
4will decompose back into ��
2.

45. LAW OF CHEMICAL EQUILIBRIUM
2��
2??????�
2�
4(??????)
Step-by-Step Breakdown
2. Reaching Equilibrium:
At equilibrium, the rate of the forward reaction (2��
2
forming �
2�
4) equals the rate of the reverse reaction (�
2�
4
decomposing into 2��
2).
The concentrations of ��
2and �
2�
4remain constant, even
though both reactions continue to occur.

46. LAW OF CHEMICAL EQUILIBRIUM
2��
2??????�
2�
4(??????)
Step-by-Step Breakdown
3. Equilibrium Constant (??????
??????)
The equilibrium constant for this reaction is given by:
??????
??????=
[�
2�
4]
[��
2]
2
Here, �
2�
4is the concentration of dinitrogen tetroxide,
and ��
2is the concentration of nitrogen dioxide at
equilibrium.

47. LAW OF CHEMICAL EQUILIBRIUM
Example Calculation
Suppose at equilibrium, the concentration of ��
2is 0.5 M
(molar) and the concentration of �
2�
4is 0.25 M.
The equilibrium constant (??????
??????)can be calculated as:
??????
??????
0.25
(0.50)
2
=
0.25
0.25
=1

48. LAW OF CHEMICAL EQUILIBRIUM
Example Calculation
Suppose at equilibrium, the concentration of ��
2is 0.5 M
(molar) and the concentration of �
2�
4is 0.25 M.
The equilibrium constant (??????
??????)can be calculated as:
??????
??????
0.25
(0.50)
2
=
0.25
0.25
=1

49. LAW OF CHEMICAL
EQUILIBRIUM
Significance in Food Chemistry
Food Packaging: Nitrogen
dioxide and dinitrogen
tetroxide are involved in the
formation of nitrogen-based
preservatives, which help in
extending the shelf life of
packaged foods by inhibiting
microbial growth.

50. LAW OF CHEMICAL
EQUILIBRIUM
Significance in Food Chemistry
Preservation: Understanding the
equilibrium between these
gases helps in optimizing
conditions for the preservation
process, ensuring the right
balance of preservatives is
maintained.