Chemistry of Life: Soaps and Cleaning Agents

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Questions and Answers

What property of liquids is responsible for surface tension?

Solubility

Cohesion (correct)

Viscosity

Density

What is the process through which soap is made from fats and oils?

Fermentation

Esterification

Hydrolysis

Saponification (correct)

Which of the following is a primary ingredient used in the production of soap?

Sodium bicarbonate

Sodium hydroxide (correct)

Potassium chloride

Calcium hydroxide

What likely effect do detergents have when added to water?

They reduce surface tension Signup and view all the answers

Which type of soap molecule is produced during saponification?

Sodium salts of fatty acids Signup and view all the answers

Which of the following statements is true about surface tension in liquids?

It affects only the surface layer of molecules. Signup and view all the answers

What is the annual market size of personal care and household products estimated to be?

$450 billion Signup and view all the answers

What historical method contributed to the discovery of soap?

Heating goat fat with wood ash extract Signup and view all the answers

How do soap molecules interact with oily and greasy dirt?

They encapsulate dirt in micelles Signup and view all the answers

Why are sodium salts of fatty acids with 10-18 carbons considered the best for soap?

They provide optimal cleansing properties Signup and view all the answers

What happens to the hydrophobic tails of detergent molecules when they disrupt the surface tension of water?

They protrude out of the water's surface. Signup and view all the answers

Which type of surfactant is known to bear negatively charged hydrophilic heads?

Anionic surfactants Signup and view all the answers

What is the main purpose of micelles formed by detergents?

To trap oily dirt within their hydrophobic interiors Signup and view all the answers

What is the primary function of skin care products?

To promote attractiveness and improve appearance Signup and view all the answers

What happens when the cells in the epidermis of the skin die?

They become the outer layer called the stratum corneum. Signup and view all the answers

What is the main ingredient in most antiperspirants that helps reduce sweat release?

Aluminium cations Signup and view all the answers

In hair care, what is the function of conditioners?

To replace lost moisture and nutrients Signup and view all the answers

What is the active role of UV absorbers in sunscreens?

To absorb UV radiation and convert it to heat Signup and view all the answers

What do the three notes in modern perfumes refer to?

The layers of scent experienced over time Signup and view all the answers

What chemical component in the skin helps to regulate body temperature?

Melanin Signup and view all the answers

What determines whether a lotion is a water-in-oil or oil-in-water emulsion?

The ratio of water to oil content Signup and view all the answers

What characteristic of organic dyes in coloring cosmetics makes them effective?

They have complex molecular structures. Signup and view all the answers

What is the primary byproduct of the saponification process when making soap?

Glycerol Signup and view all the answers

Which molecular structure is essential for effective cleaning with soap?

Fatty acid sodium salts Signup and view all the answers

How do soaps primarily help in cleaning oily and greasy substances?

By encapsulating dirt in micelles Signup and view all the answers

What role do cohesive forces play in surface tension?

They create a greater density of molecules at the surface. Signup and view all the answers

What occurs when detergents are added to water?

They create a monolayer at the surface. Signup and view all the answers

What characteristic of the surface molecules contributes to surface tension?

Their strong intermolecular bonds Signup and view all the answers

Which of the following is the primary market focus for cleaning agents and detergents?

Personal care and household products Signup and view all the answers

Which historical item is associated with the early production of soap?

Animal fats and wood ashes Signup and view all the answers

What is the effect of surface tension on small aquatic organisms?

It prevents them from sinking. Signup and view all the answers

Why are fatty acids with 10-18 carbon chains favored for soap production?

They effectively emulsify grease. Signup and view all the answers

What is the primary role of surfactants in cleaning products?

To lower surface tension of water Signup and view all the answers

How do micelles function in the removal of dirt?

By trapping oily dirt within their hydrophobic interiors Signup and view all the answers

What characterizes anionic surfactants?

They have a negatively charged hydrophilic head Signup and view all the answers

What aspect of skin does the stratum corneum represent?

The outermost layer of dead cells Signup and view all the answers

What percentage of the total weight of personal care products are fragrances?

1% Signup and view all the answers

What role do sebaceous glands play in hair care?

They provide lubrication to hair Signup and view all the answers

Which type of UV radiation is primarily responsible for causing sunburn?

UVB Signup and view all the answers

What is the purpose of Aluminium cations in antiperspirants?

To kill bacteria and prevent odor Signup and view all the answers

What indicates that a lotion is a water-in-oil emulsion?

First ingredient listed is an oil Signup and view all the answers

Which fragrances are characterized as having a longer-lasting scent?

Base notes Signup and view all the answers

What does the Sun Protection Factor (SPF) measure?

Protection against UVB radiation Signup and view all the answers

What is a primary component of hair that contributes to its strength?

Keratin Signup and view all the answers

How do modern perfumes allow us to smell them?

Through evaporation and mixing with air Signup and view all the answers

Study Notes

UGEB2380: The Chemistry of Life (2024-25)

Course offered by Dr. Sam CK HAU, Chemistry Department
Covers Cleaning Agents, Personal Care, and Cosmetics

Cleaning Agents, Personal Care, and Cosmetics Industry

Extensive market for personal care and household products
Annual market size is nearly 450 billion US dollars (and growing)
Includes soaps, shampoos, toothpastes, mouthwashes, cosmetics, moisturisers, laundry detergents, and household cleaners

Surface Tension

Property of liquids, causing them to behave as if they have a thin membrane.
Molecules in liquids exert cohesive forces on neighbouring molecules.
Water molecules at the surface exert stronger attraction forces on neighbouring molecules compared to those submerged in the water. This creates a tension at the surface.

Soaps and Detergents

Romans are believed to have discovered soaps.
Soaps are made by heating goat fat with extracts of wood ashes (containing strong bases)
Soaps help remove oily and greasy dirt from various surfaces (including skin, hair, fabrics, and dishes)

How Soap is Made

Involves hydrolysis of naturally occurring fats and oils, using a base like sodium hydroxide.
Results in alcohol and the salt of a carboxylic acid.
This process is called "saponification."
Sodium salts of fatty acids (with 10-18 carbon chains) are the most effective soaps.

Effect of Detergents

Detergent molecules disrupt the cohesive forces between water molecules at the surface. This process reduces surface tension.
Nonpolar (hydrophobic) tails of detergent molecules push outwards from the water surface.
Polar (hydrophilic) heads of detergent molecules stay embedded among water molecules at the surface..

Surfactants and Micelles

Substances that accumulate at water surfaces, altering surface properties drastically, often lowering tension.
Detergents aggregate into micelles within water.
Micelles form microscopic spheres with hydrophobic tails pointing inwards and hydrophilic heads pointing outwards, shielded from water molecules.

How Detergents Clean

Water must penetrate fabrics to clean effectively .
Detergents lower water's surface tension to enable water to penetrate fabric and carry detergent micelles into the fabric.
Micelles trap oily dirt within their hydrophobic interiors.
When micelles become coated with grease, they are dispersed in the water and removed through rinsing.
Micelles are negatively charged due to carboxylate groups (-CO₂⁻).

Types of Surfactants

Common structure: hydrophobic tail and hydrophilic head.
Anionic surfactants have negatively charged heads.
Cationic surfactants have positively charged heads.
Nonionic surfactants have no electrical charge

Cosmetic and Skin Care

Aims to improve appearance and body odor.
Includes henna-extracted dyes, cosmetic preparations, and various products.
Includes anything applied to the body for cleansing, beautifying, promoting attractiveness, or altering appearance.

Cosmetic and Skin Care Categorisation

Four main categories: hair care, skin care, hand/face/body soaps, and perfumes/colognes.
Raw materials like detergents, moisturisers, fragrances, and solvents account for a significant portion of the retail costs. Other costs include packaging, distribution, marketing, and research and development expenses.

Cosmetic and Skin Care — Key Components

Surfactants are critical components in soaps, shampoos, and toothpastes.
Fragrances contribute less than 1% to the total weight of personal care products but constitute 25% of the raw-material costs.

Skin Care

Skin is the largest organ in the body, covering the body and protecting from damage.
Regulates body temperature and senses external stimuli.
Synthesizes components like vitamin D.
Composed of two basic layers: epidermis and dermis.

Skin Care - Epidermis and Stratum Corneum

Epidermis is the outermost layer composed of multiple layers of dead cells.
Stratum corneum is the outermost layer of dead, lifeless cells.
Conditions like water content affect skin health, impacting moisture levels, and susceptibility to microbes and irritation.

Skin Lotions

Emulsions of two or more insoluble liquids, intended to keep skin soft and moist.
Classified as either water-in-oil or oil-in-water emulsions, depending on the main ingredient noted first.

Antiperspirants and Deodorants

Body controls temperature through perspiration (sweating) and its evaporation.
Eccrine glands produce sweat, containing inorganic ions, lactic acid, urea, and glucose.
Apocrine glands release odorless secretions, which can generate unpleasant odors through bacterial interaction.
Antiperspirants contain aluminium compounds which reduce sweat production.
Deodorants mask odors with fragrances and antibacterial agents.

Colouring Cosmetics

Includes lipsticks, eye colourings, nail polishes, and face powders.
Dyes and pigments are categorized as organic or inorganic.
Organic dyes commonly use highly conjugated structures.
Inorganic dyes, often transition metal ions, absorb or scatter light to produce color.

Fragrances

Perfumes are concentrated mixtures of synthetic/natural chemicals dissolved in alcohols.
Colognes have a more dilute mixture compared to perfumes.
Fragrances are volatile, allowing them to mix with air and be sensed.
Rate of fragrance evaporation varies due to chemical structures and body warmth.

Fragrance Notes

Fragrances typically have top, heart, and base notes to allow for specific experiences based on the different evaporation rates of chemical compounds.

Sunscreen

Protects skin from UV radiation (UVA and UVB).
UVA damages deeper collagen and elastin fibres and can cause premature aging.
UVB, which is more energetic, causes skin burning and is a key factor in skin cancer development.
Skin's melanin is a defence mechanism against UV radiation, reducing radiation damage.

Sunscreen - UV Absorbers and Scattering Agents

UV absorbers are organic compounds that absorb UV radiation (PABA, avobenzone, octocrylene).
Scattering agents are inorganic compounds that scatter UV radiation, typically zinc oxide or titanium oxide.

Sun Protection Factor (SPF)

SPF is a measure of sunscreen's ability to protect from UVB radiation.
Higher SPF values correlate with stronger protection.
Products labeled as SPF 30 reduce UVB by a factor of 30 (compared with no protection).

Hair Care

Serves to help protect the skin and regulate the temperature of the body.
Keratin, the main protein in hair structure, dominates hair structure.
Sulphur containing cysteine amino acids are essential elements for strength.
Disulfide linkages provide strength within and between chains.

Hair Structure

Hair is composed of a central core (cortex), covered by a scaly outer sheath (cuticle), also lubricated by oily sebum (produced by sebaceous glands)
Sufficient sebum is essential to prevent drying/damage to the cuticle.

Hair Treatment

Permanent wave treatments, use reducing agents to break disulphide bonds.
Hair relaxers use alkaline compounds to disrupt disulphide bonds.

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Description

Explore the chemistry behind cleaning agents, personal care, and cosmetics in the course UGEB2380. This quiz will cover topics from surface tension to the historical context of soaps, including their composition and market significance.