Chemistry P2 Key Info

•  Fuels are compounds of hydrogen and carbon
• Carbon and hydrogen are oxidised
• Energy is released
• Waste products are produced, which are released into the atmosphere
• High temps mean nitrogen oxides can form which cause respiratory problems and acid rain 

Incomplete combustion= carbon monoxide + particulates released
(carbon monoxide- colourless, odourless and toxic)
(Particulates- cause global dimming + damage to lungs)

-OH

Methanol

Ethanol

Propanol

Butanol

• 
  Dissolve in water to form neutral solutions
• React with sodium to produce hydrogen
• Burn in air to produce carbon dioxide and water
• Are used as fuels and solvents

RP: Chromatography

1.     Draw a start line in pencil on absorbent paper

2.     Put samples of five known colourings and the unknown on the start line

3.     Dip the paper in a solvent

4.     Wait for the solvent to travel to the top of the paper

5.     Identify the unknown by comparing the horizontal spots with the results of the others.

Rf value- used to identify the components in a mixture

Different components have different Rf values

Rf= distance moved by substance/ distance moved by solvent

Waste Water treatment

·      Screening and grit removal

·      Sedimentation to produce sewage sludge and effluent

·      Anaerobic digestion of sewage sludge

·      Aerobic biological treatment of effluent

Prevented:

§  Painting, electroplating or greasing a metal

§  Aluminium objects are protected by a thin layer of aluminium oxide

Sacrificial protection:

§  more reactive metal placed in contact with the metal:

§  Blocks of more reactive magnesium are attached to the iron/steel object

§  Magnesium is more reactive so reacts+ loses electrons instead of the iron

Galvanising:

§  The object is coated in a layer of zinc

§  The zinc layer stops oxygen and water from reaching surface

§  Zinc also provides sacrificial protection