Unit 3: Chemistry in Society Flashcards
Elements essential in Fertilisers
Nitrogen (N)
Phosphorus (P)
Potassium (K)
Natural Fertilisers
Decay of dead plants + animals
Decay of plant + animal waste
Synthetic Fertilisers
Ammonia (Haber Process)
Nitric Acid (Ostwald Process)
Haber Process
Nitrogen + Hydrogen ⇔ Amonia
450ºC
200 atm
Iron Catalyst
Solubility
Fertilisers are usually very soluble and can be washed into rivers and lochs, increasing pollution
Ammonia
Invisible gas with a characterstic smell. Very soluble and produces an alkaline solution. Released when ammonium compounds are heated with an alkali
Ammonia + Acid
Forms ammonium salts
Nitric Acid
Formed when brown gas nitrogen dioxide dissolves in water
Nitrogen Monoxide
Formed from nitrogen and oxygen in a lightning storm
Heavy Elements
Formed from lighter elements in stars
Radioactive Elements
Become more stable by giving out alpha, beta or gamma radiation
Nuclear Equations
Written to describe nuclear reactions
Half-Life
Time taken for half of the nuclei of a particular isotope to decay
Use of Radioactive Isotopes
In medicine Cobalt-60 is used to kill cancer cells
Alpha Particles (α)
Made of 2 protons and 2 neutrons (identical to helium nucleus). Heavy and Positively charged
Beta Particle (β)
Made of 1 very fast moving electron. Light and negatively charged
Gamma Ray (γ)
Part of the E-M spectrum. Has no mass, travels at the speed of light and has a very high frequency so a very high energy
Ionisation
When an atom loses or gains an electron giving it a charge
Alpha Penetration
Stopped by a few cm of air or a thin sheet of paper
Beta Penetration
Stopped by a thin sheet of aluminium
Gamma Penetration
Stopped by Lead or Concrete
All metals
Conduct electricity when solid or liquid
Metals are good conductors of
Heat
Density
How heavy a metal is
Malleability
How easily a metals shape is changed
Metal + Oxygen
→ Metal Oxides
Metal + Water
→Hydrogen + Metal Hydroxide
Metal + Acid
→Hydrogen + Salt
Unreactive Metals
Like mercury and silver (at the bottom of the ECS)
Can be obtained from ores by heat alone
Moderately Reactive Metals
Obtained from their ores by heating with carbon
Reactive Metals
Metals above zinc need to be extracted by other methods
Reactive Metals’ Oxides
Form strong bonds with oxygen and so are difficult to reduce
Displacement Reaction
Occurs when a metal higher in the ECS is added to a solution of ions of a metal lower in the ECS. Higher metal atoms lose electrons forming ions and lower metal ions gain electrons forming atoms
Copper Ions Colour
Blue
Corrosion
Chemical reaction that occurs on the surface of metals
Rust Requirements
Oxygen and Water
Ferroxyl Indicator
Can detect the presence of the corrosion of iron. Amount of blue colour formed inicates how much rusting has occured
Preventing Rust
Supply electrons to iron
Sacrificial Protection
Physical Barrier
Galvanising
Sacrificial Protection
More reactive metal attached to iron and corrodes instead of the iron
Electroplating
Coating a metal object with a layer of another metal
Physical Barrier
Iron Covered with:
- Zinc
- Tin
- Plastic
- Paint
- Oil
Electricity
Flow of electrons through a wire
Rechargable Battery
When electricity is passed through them, the energy is stored as chemical energy
Eg. Lead/Acid
Cell
Arrangement of two metals connected by wires to a meter with a wet filter paper placed between them
Electrolyte
Conducting substance which connects and completes the circuit
Ion Bridge
Conducting link which completes the circuit as it allows ions to move carrying the current between the two halves of the cell
Oxidation
Reaction involving the loss of electrons
Reduction
Reaction involving the gain of electrons
Redox
Whole Reaction (Oxidation + Reduction)
Synthetic Fibres
Polymers which show a wide range of useful properties. Man made
Thermosoftening Plastics
Can be melted and reshaped
Thermosetting Plastics
Cannot melt again and will decompose if heated strongly
Biodegradable
Will rot when buried
Few plastics are
Biodegradable
Biodegradable Plastics - Advantage
Reduce waste in landfill sites
Polymerisation
When monomers join up to form polymers
Simplest alkene
Ethene - the starting material for many polymers
Making ethene
Made from naptha
Made from various long chain hydrocarbons which come from oil by cracking
Cracking ethane from natural gas
Common Addition Polymers
Poly(ethene)
Polystyrene
P.V.C
P.T.F.E
Addition Polymerisation
a process involving many small, unsaturated monomers combining to form one large polymer molecule.
Repeating Unit
Part of a polymer whose repetition would produce the complete polymer chain
Condensation Polymer
An alcohol reacts with a corboxylic acid to make an ester
Formation of ester links
Formed by the Reaction of the hydroxyl and the carboxyl functional groups
Polyesters
Condensation Polymers
Many condensation Polymers are made from
Monomers with 2 functional groups in the molecule
All compounds of the group 1 metals are
Soluble
All ammonium compounds are
Soluble
All nitrate compounds are
Soluble
Precipitation Reaction
Reaction between two solutions to form an insoluble salt
Analytical Techniques
Flame Tests
pH measurement
Chromatograhy