Carbon Chemistry

What’s so special about Carbon? Fourth most abundant element in the universe. Essential to life on earth. Many different forms… carbon dioxide (CO 2 ), limestone (CaCO 3 ), wood, plastic, diamonds, and graphite.

Carbon – The Element of Life Unique atomic structure… form covalent bonds with up to four other atoms. Elements with either less or more than 4 valence electrons can only form a maximum of 3 covalent bonds, this is why 4 is a magic number and why carbon is special. Lightest element with four valence electrons

Organic Compounds Organic compounds are those compounds found in any organism that is living or was once living. Chemically… Organic compound – any compound that contains the elements carbon and hydrogen. Inorganic

Carbon Compounds Carbon can be bonded covalently to up to four other atoms, but what a carbon is bonded to can be very simple or very complex. Hydrocarbons – when a carbon atom is bonded only to hydrogen atoms. Gasoline and fossil fuels are examples of hydrocarbons Carbon chains – when many carbons are bonded together to make long chains or rings. Often consist of many hydrocarbons bonded together called polymers

Properties of Hydrocarbons Hydrocarbons are the simplest organic compounds, made up of only two elements -- they have low melting and boiling points -- hydrocarbons are flammable and tend to burn in combustion reactions -- hydrocarbons mix poorly with water (they are nonpolar) -- hydrocarbons are used for many of our fuels such as heating oil, diesel fuel, gasoline, coal and methane.

What are “polymers”? A polymer is a large molecule that is created when monomers are joined together. A monomer is a single unit that is used to build a polymer. Polymers may be naturally occurring or man-made (synthetic).

Polymerization

Polyethylene (PE) used for: flexible bottles, ice trays, plastic bags Some examples of synthetic polymer structures:

Polyvinyl Chloride (PVC) used for: pipes, bottles, CD’s, computer housings

Polypropylene (PP) used for: rope, luggage, carpet, film, polar fleece propylene

Polystyrene (PS) used for: toys, packaging, egg cartons, flotation devices, hot cups

Vulcanizing Rubber to make it more flexible, tougher and temperature resistant and involves adding Sulfur atoms to create cross-links.

Properties of Polymers Properties are determined by the structure of the molecules and depend on: -type of monomers used -chain length -branching -degree of cross-linking

Natural and Synthetic Polymers

Some Natural Polymers in Food… Gelatin in gummi worms and gummi bears are made from natural polymers! Bubble gum contains styrene butadiene rubber! Carbohydrates (starches) and proteins are examples of natural polymers! natural polymers

Polymers are everywhere!!! Polymers at the movies…. Nylon carpet, polyester and acrylic seats, polyester curtains, nylon screen, polyester film strip, waxy polyethylene popcorn tub, starch in popcorn, polystyrene cups, plastic M&M bag, protein in hotdogs, gelatin in gummy bears, paraffin in Junior Mints, sticky stuff on the floor made of soda, butter, Skittles, Milk Duds and more…

Properties of Polymers Properties are determined by the structure of the molecules and depend on: -type of monomers used -chain length -branching -degree of cross-linking

Branching creates more flexibility; less rigid plastic Low density polyethylene has more branches, so it cannot be packed as closely as in linear, high density polyethylene.

Branching and Cross-links affect strength DIRECTION OF INCREASING STRENGTH

Polymer Structure Branched, Cross-linked or Linear?

Where does the material to make polymers come from? Materials produced from the “cracking” of petroleum are the starting points for the production of many synthetic compounds like polymers. Cracking is the process whereby complex organic molecules such as heavy hydrocarbons are broken down into simpler molecules.

Carbon technology: Risks and Benefits?!? Benefits: -Plastics are used in many useful products, including medical uses -Synthetic fibers have better properties than natural fibers -Pharmaceuticals are produced from hydrocarbons -Fossil fuels are “easy” sources of energy -…. Concerns: -Uses up non-renewable resources -Problems with petroleum acquisition and refining processes -Creates long-lasting waste (6-pack rings, non biodegradable material) -Burning hydrocarbons creates CO 2 -….

The Carbon Cycle Elements such as Carbon exist in fixed (limited) amounts on the earth and are located in various chemical pools called reservoirs. The movement of carbon, in its many forms, between the atmosphere, oceans, biosphere, and solid earth is described by the carbon cycle. This cycle is driven by both the Earth’s internal (geothermal) energy, and the external energy from the sun and can be divided into geological, chemical and biological components.

The global carbon cycle Reservoirs (in black) are gigatons (1Gt = 1x10 9 Tons) of carbon, and fluxes (in purple) are Gt carbon per year. Sources and sinks of carbon will add or remove carbon from the active part of the cycle. Carbon sinks include long-lived trees, limestone (formed from shells of small sea creatures that settle to the ocean bottoms, plastic, and the burial of organic matter (form fossil fuels). Carbon sources include the burning of fossil fuels and other organic matter, the weathering of limestone rocks (CO 2 released), volcanic activity, forest destruction, and the respiration of living organisms.

Combustion Rapid chemical combination of a substance with oxygen, producing heat and light. Burning Exothermic chemical reaction.Exothermic Creates heat (light glowing/flame)Creates heatlight glowingflame Fuels = organic compounds (especially hydrocarbons) in the gas, liquid or solid phase. hydrocarbons liquid

As long as there is enough oxygen available this reaction will take place as described in the balanced equation. However, If the amount of oxygen is limited then some of the small segments and Carbon monoxide molecules that were produced will not get used up. This is referred to as “Incomplete Combustion”.