Chemicals that changed world

Michael Široký

Polyethylene It was first synthesized by Hans von Pechmann in

1898 while heating diazomethane- accident, next big step was during World War II.

Properties: melting point: 105-130°C, soluble in selected solvents

For industry it is a very common material, also used in casual life

Consists of ethylene monomers It is formed by polymerization only upon contact

with catalyst titanium(III) chloride (Ziegler- Natta), chromium(VI) oxide on silica

Types of PE There are a big number of different types of PE:

HDPE, LDPE, UHMWPE, ULMWPE,PEX,....

UHMWPE: produced by using Ziegler´s catalyst, molecular weight is between 3.1 and 5.67 million = very tough material

HDPE: produced by chromium, metallocene or Ziegler´s catalyst, density is 0.941 g/cm3, third of all toys are manufactured from HDPE, packaging

PEX: degree of cross-linking is 65-89%, three types PEX-A, B, C

Estimated time of degradation of PET bottle is 500 years

Petrol Fossil fuel formed milions years ago Mixture of many hydrocarbons. Consist of: naphthenes (also called cycloalkanes),

alkanes(pentane- octane), alkenes and aromatics. Isolated by fractional distillation (straight-run gasoline;

reformate; cat cracked gasoline; isomerate;...) 2 C8H18(l) + 25 O2(g) → 16 CO2(g) +

18 H2O(g) + 10.86 MJ/mol

Incomplete combustion: CO, NO, NO2,...=photochemical smog

Octane rating is measurement of quality (it expresses resistance to autoignition)

Antiknock aditives for high compression combustion- tetraethyl lead found byThomas Midgley and Harry Ricardo

Nowadays are used ethers or aromatics

•More volatile than diesel(caused by additives)

•In USA is consumed approx. 1,3 billion liters of gasoline every day

Soap Base ingredient is sodium palmitate

C15H31COOH+ NaOH = C15H31COO–Na+

The main raw materials required for the manufacture of ordinary soap are:

Animal fat or Vegetable oil Sodium hydroxide (Caustic soda) Sodium chloride (Common salt)

In hard water is soap not so effective as it is in soft water because calcium an magnesium ions are present

In water sollution molecules of soap arranges into clusters called micelles.

Further use of soap

Napalm Liquid soap Detegrents Unusual use at household-

bug repellent, deodorizer, lubricant at metal surface connection

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