Senior Science Essay

Submitted By maddy_ross
Words: 2071
Pages: 9

9.2
Lifestyle Chemistry

Chemicals in Daily Life
(9.2.1 – L1 S1)
Chemicals
Many times everyday people use chemicals to perform various tasks.
Eg – milk, soap, toothpaste
Groups of Chemicals
To help us better understand these products, we need to learn about the types of chemicals they contain.
To do this it is best to sort chemicals into groups based on their function in the product.
Surfactants
Commonly called detergents.
Main ingredients in most cleaning products.
Break up fats and help to wet dirty surfaces.
Products include washing detergents and surface cleaners.
Degreasers
Dissolve oils, fats, and greases which are not soluble in water.
Contain solvents such as hexane that oils can dissolve in.
Mostly used in automotive products.
Lubricants
Reduce friction and wear on moving surfaces.
Usually oil or silicon based.
Can be liquid (engine oil) or solids (grease).
Commonly used in car engines.
Pesticides
Selectively kill animals considered to be a nuisance.
Work in a variety of ways including poisoning, interfering with nervous system.
Some are synthetic (DDT) while others are sourced from plants (pyrethrum).
Solvents
Liquids used to dissolve other substances.
Used in cleaning products (window cleaner), pesticides (to carry the poison) and other applications (mineral turpentine).
Can be polar (water) or non-polar (hexane).

Metal Cleaners
Specialty chemicals used to clean specific metals (stainless steel).
Remove tarnish, a dull layer of metal oxide that forms when metals react with oxygen in the air.
Often utilise an abrasive, small particles that remove the surface layer.
Hygiene Products
Large range of products including soaps, shampoo, toothpaste, skin care, sunscreen etc.
Many clean oil and dirt from the outer surface of the body.
Often a mixture of many chemicals
Pharmaceuticals
Products that alter biochemical processes in our body.
Enormous range of different chemicals.

Solutions Colloids and Suspensions
(9.2.1 L2 L3)
Chemicals
Many household products are a mixture of different chemicals that are combined together.
A mixture is defined as a material containing more than one type of product.
Liquid mixtures can be classified into three main groups (solutions, colloids, suspensions).
Solution
At least one substance (the solute) dissolved in another substance (the solvent).
Examples include salt water and cordial.
Solutions can be; solid in liquid (saltwater) or gas in liquid (oxygen dissolved in water).
Solutions are a homogenous mixture (i.e they are uniform).
The individual particles are dissolved within the solution so light passes through (i.e the solution appears clear), the particles cannot be removed from the solution by filtration and the particles will not settle out over time.
Suspension
Non-uniform mixtures (heterogeneous) of one or more materials with a liquid.
The particles of the suspended material are large and not permanently dissolved in the liquid.
Examples include paint and salad dressing.
Because the particles are larger suspensions will settle out into distinct layers after a period of time and scatter light that passes through them, therefore they appear cloudy or opaque.
Suspension can be solid particles suspended in a liquid (like silt in water) and liquid particles suspended in a liquid (like fresh milk).
Colloids
Contain particles that are larger than those in solutions, but smaller than those in suspensions.
Properties are halfway between the two.
Colloids are not completely homogenous mixtures but they remain stable for long periods of time.
Examples include homogenised milk.
There are many different types of colloids; foams – Gas in a liquid (shaving cream), solid in liquid (paint), emulsion – liquid in liquid (mayonnaise) – Often a mixture of two liquids that do not mix easily. To assist mixing an emulsifying agent is often added (like the egg in mayonnaise).

Surface tension
(9.2.1 L4…