| In fact all matter on Earth is made of
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| | lead crystal, which contains typically
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| chemical substances and every material
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| | 16% PbO: and stained glass, which
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| thing is a chemical or a mixture of
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| | contains various elements selected from
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| chemicals. Our home is a virtual
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| | the transition elements from Ti to Cu,
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| chemistry laboratory of fascinating
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| | depending on the desired color.
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| products derived from raw materials such
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| | Â
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| as the water, soil, rock, etc found in
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| | Â Though nails aren't very high-tech
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| the biosphere of our planet. If we just
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| | materials, we all know how necessary they
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| scratch the surface of all the hundreds
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| | are not only for successful constructions
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| of chemical substances used in every
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| | bur also a number of purposes. Most nails
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| home, it will open our eyes to the
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| | are made of steel, which is an alloy
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| importance of chemical synthesis,
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| | containing mostly iron and carbon. Nails
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| engineering, manufacturing, and
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| | that are never expected to be in contact
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| distribution of the substances used in
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| | with water are plain steel, but nails
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| our everyday life. Our homes, apartments,
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| | used in installing shingles or external
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| schools, offices, parks, rails, cars,
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| | panels must be made resistant to rust. To
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| buses, airplanes and subways all these
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| | prevent their rusting, steel nails are
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| are our' home' at one time or another as
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| | often galvanized. This means that they
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| these are all just small parts of the
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| | are coated with zinc, a good reducing
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| home that we all share of our one, real
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| | agent so that rather than the iron being
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| home, the "Spaceship Earth" and through
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| | oxidized, the zinc will oxidize and the
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| our study of chemistry, together we
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| | steel will not rust. Since zinc melts at
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| appreciate how that one precious home is
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| | a temperature (4190C) much below the
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| truly a "World of Chemistry, a World of
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| | melting point of iron (15350C), steel
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| Choices".
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| | nails can simply be dipped into molten
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| Wood is mostly cellulose with the smaller
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| | zinc, removed, and cooled.
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| amounts of hemicelluloses and lignin. All
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| | Another option for rustles nails is to
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| of these compounds are synthesized to be
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| | use aluminum instead of steel. There is a
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| the structural parts of trees and are
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| | crucial difference between the products
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| made via photosynthesis from carbon
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| | formed when iron and aluminum react with
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| dioxide and water. Cellulose is simply
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| | oxygen. While iron forms the
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| glucose molecules linked together in the
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| | characteristic red rust, Fe2O3, which
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| beta form to make long-chain molecules.
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| | flakes off and allows more iron to
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| Hemi cellulose differs from cellulose in
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| | contact the air, aluminum also forms its
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| that the sugar molecules of which it is
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| | oxide, Al2O3, but this oxide adheres
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| composed contain only five carbon atoms
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| | tightly to the metal and prevents oxygen
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| rather than six, the missing carbon atom
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| | from reaching the rest of the metal.
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| being the one that is not part of the six
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| | Aluminum is not as strong as steel so is
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| membered rings. Lignin is very different;
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| | seldom used for structural purposes.
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| it is a polymer of several aromatic
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| | However, besides being light weight, it
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| alcohols such as conifer alcohol and
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| | is valuable for adding to decoration.
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| vanillin.
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| | Â
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| Glass is an amorphous mixture of the
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| | People often speak of cement and concrete
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| oxides of Silicon (SiO2), Calcium oxide
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| | as if they were the same thing, but they
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| (CaO) and sodium oxide (Na2O). We know
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| | are actually different substances.
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| that mixtures are not compounds because
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| | Concrete is the substance we drive on and
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| the composition of a mixture is not
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| | it is made from cement, sand or gravel
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| fixed, but rather can vary over wide
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| | and water. The mixing of these three
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| ranges. White sand is nearly pure SiO2
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| | ingredients is done shortly before the
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| and is used directly in glass
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| | wet concrete is put in place to harden.
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| manufacturing whereas sodium and calcium
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| | Cement on the other hand, is made by
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| oxides are formed by heating sodium
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| | heating clay (typically Al2O3 .2SiO2.
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| carbonate and calcium carbonate,
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| | 2H2O) and limestone (CaCO3) until they
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| respectively
| |
| | begin to melt at about 12600C. This melt
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| Na2CO3 Â Â Â Â Â Â Â Â Â Â Â
| |
| | is called clinker and is then cooled and
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| Â Â Â Â Â Â Â Â Â Â Â Â Â Â
| |
| | powdered to form what is sold
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| Na2O + CO2
| |
| | commercially as Portland cement. Although
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| CaCO3Â Â Â Â Â Â Â Â Â Â Â Â
| |
| | cement is not a pure compound, a typical
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| Â Â Â Â Â Â Â Â Â Â Â Â Â Â
| |
| | clinker compound is Ca3SiO5, which is
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| Â CaO + CO2
| |
| | more clearly written as 3CaO .SiO2.
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| These ingredients are heated together
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| | We may believe it or not, even though
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| until they all melt and dissolve
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| | concrete and cement have been used for
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| together. The mixture is then cooled
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| | millennia, there is still disagreement
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| slowly until the glass stiffens, it does
| |
| | about what exactly happens when a mixture
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| not crystallize, so it is often spoken of
| |
| | of sand, water, and Portland cement is
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| as a super-cooled liquid rather than as a
| |
| | allowed to set and harden. It is clear
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| solid. In ordinary window glass, the mole
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| | that the water reacts with CaO and Al2O3
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| ratio of the oxides is about 1.6 moles of
| |
| | to make Ca(OH)2 and Al(OH)3 which react
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| Na2O to 1.0 moles of CaO to 6 moles of
| |
| | with calcium silicates to form calcium
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| SiO2. Glass for other purposes utilize
| |
| | aluminosilicate crystals, which interlock
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| different ratios and often include other
| |
| | with each other. Concrete sets in a
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| oxides. Well-known examples are Pyrex
| |
| | matter of hours and then continues to
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| glass, which includes 12.5% boron-oxide;
| |
| | harden for years.
|
