Mod 6 + 7 Assessment: Soaps, Detergents, and Polymers

More Crystalline Structure

More intermolecular forces → more rigid

Soaps Formation

Forms from base-driven hydrolysis of fats (triglyceride)

Triglycerides

Made up of 3 fatty acid molecules and a glycerol molecule

Fatty Acid

Carboxylic acids with a long carbon chain, can be either saturated or unsaturated

Glycerol

An organic molecule that contains 3 alcohol functional groups, also soluble in water; also called 1,2,3-tripropanol

Base Driven Hydrolysis

Hydrolysis when esterification is reversed by adding 3 water molecules to the triglyceride, using a strong base like NaOH instead of water

Salt Molecule Formula

R-COO-Na, which is the formula for soap

Soap Definition

A sodium or potassium salt of a long chain fatty acid

Properties of Soaps

Tail is hydrophobic, head is hydrophilic, biodegradable, cannot be used in acidic solutions, forms scum in water with Ca2+ or Mg2+ ions

Detergents

Like soaps but synthetic, created to make up for the disadvantages of soap

Types of Detergents

Anionic, Cationic, Nonionic

Anionic Detergent

Non polar tail, polar and negatively charged head, creates lots of foam

Anionic Detergent Uses

laundry detergents and dishwashing liquid

Cationic Detergent

Non polar tail, polar and positively charged head

Cationic Detergents Uses

hair conditioners, fabric softeners, antiseptics and disinfectants

Nonionic Detergent

Non polar tail, polar head with no charge, forms hydrogen bonds with water, very soluble in water

Nonionic Detergent Uses

front loading washing machines and dishwashing liquids

Anionic Head Example

R-SO3- Na+

Cationic Example

R-N(CH3)3+ Cl- (tertiary ammonium ion)

Nonionic Example

R-OCH2OCH2OCH2OCH2OH

Differences Between Soaps and Detergents

Soaps are made from biomass, cannot be used in hard water or acidic solutions; Detergents are made synthetically, can be used in both hard water and acidic solutions

Action of Soap

Step 1 - soap molecule structure

Hydrophilic head

Part of a soap molecule that is attracted to water.

Hydrophobic tail

Part of a soap molecule that is attracted to grease/oils.

Micelle Formation

Process where multiple soap molecules arrange around each oil droplet, creating a spherical structure.

Emulsification

The process by which micelles allow oil to suspend in water.

Polymer

A large molecule composed of many repeated subunits called monomers.

Monomer

A small molecule that can join together with other small molecules to form a polymer.

Low-density polyethylene

A type of polymer made from ethylene, used for plastic garbage bags and milk cartons.

High-density polyethylene

A type of polymer made from ethylene, used for Australian bins and blue plastic crates.

Polyvinyl Chloride (PVC)

A polymer used for water pipes and electrical wiring, known for being rigid and water resistant.

Polystyrene

A polymer used for food containers and CD/DVD cases, recognized for being a good insulator.

Polytetrafluoroethylene (PTFE)

A polymer used for frying pans, known for being heat and flame resistant.

Polyamides

A type of condensation polymer used in textiles and automotive parts, known for high tensile strength.

Polyesters

A type of condensation polymer used in clothing and carpets, recognized for high tensile strength and heat resistance.

Polyethylene terephthalate (PET)

A polyester produced from benzene-1,4-dicarboxylic acid and ethane-1,2-diol.

Nylon 6

A polyamide made from 6-aminohexanoic acid.

Nylon 6,6

A polyamide made from hexandioic acid and hexan-1,6-diamine.

Petrol

A fuel derived from crude oil with a high energy content of approximately 44 MJ/Kg.

Ethanol

A fuel produced from fermentation with a lower energy content of 27 MJ/Kg.

Environmental Impact of Petrol

Rate of CO2 production exceeds consumption by plants, contributing to global warming.

Environmental Impact of Ethanol

Considered sustainable and carbon neutral, as CO2 produced is consumed by plants.

Fermentation of glucose

The process by which glucose is converted into ethanol.

Chemical Structure of Petrol

A complex mixture of alkanes.

Chemical Structure of Ethanol

C2H5OH.

PET Properties

• high tensile strength

• can be drawn into fibres

• abrasion resistant

• heat resistant

• wrinkle resistant

• heat resistant

• hydrophobic

• thermoplastic

PET Uses

• clothing

• carpets

• fruit containers

• single use plastic bottles

Nylon 6,6 Uses

• clothing (elastic stuff)

• seatbelts

• sleeping bags

Nylon 6,6 Properties

• high tensile strength

• can be drawn into fibres

• abrasion resistant

• elastic

• thermoplastic

• absorbs moisture

Phenolphthalene

pink —> colourless - 8.3-10

Bromothymol Blue

blue —> yellow 6.0-7.6

Phenol Red

red —> yellow 6.8-8.0

Methyl Orange

yellow —> red 3.2-4.4

HDPE Structure

straight chain

PET Structure

• chain stiffening effect present

• dipole-dipole forces

Nylon 6,6 Structure