Forces between molecules determine the properties of plastics
Strong covalent bonds hold the atoms together in long chains. But it's the bonds between the different molecule chains that determine the properties of the plastic. - thermosoftning polymers- weak force
Thermosetting polymers- strong forces
The reaction conditions - temperature- will affect the properties of a polymer.
Rate of reaction chemistry
The rate of reaction depends on 4 things
- surface area of solids
3 different ways the rate of reaction can be measured
- change in mass
- the volume of gas given off
More collisions increase the rate of reaction
1) a higher temperature, because the particles move quicker, therefore collide more often
2) higher concentration, increasing the pressure,, which means the particles are more squashed together therefore collide more
3) larger surface area, more surface area to work on, frequent collisions
Catalysts speed up reactions
A catalyst is a substance which speeds up a reaction without being changed or used up in the reaction
Exothermic reaction is one which transfers energy to the surroundings usually in the form of heat and usually in the form of heat and usually shown by a rise in temperature.
E.g burning fuels
ENDOTHERMIC reaction is one which takes in energy from the surroundings usually in the form if heat and is usually shown by a fall in temperature.
Acids and alkalis
The strongest acid has a ph 0, the strongest has a ph 14
And indicator is just a dye that changes colour
Acids and bases neutralise each other
Acid is a substance with a ph less than 7
A base is a substance with a ph greater than 7
An alkali is a base that dissolves in water.
The reaction between acids and bases is called neutralisation, acid+base Salt+water
Acids reacting with metals-
Metals react wi acids to make salts
Hydrochloric acid will always produce chloride salts
Sulfuric acid will always produce sulfate salts
Nitric acid produces nitrate salts when neutralised
Oxides, hydroxides and ammonia
Metal oxides and metal hydroxides are bases
All metal oxides and metal hydroxides react with acids to form a salt and water
Electrolysis means splitting up with electricity
If you pass an electric current through an ionic substance that's molten or in solution, it breaks down into the elements it's made of.
Electrolytes(liquid to conduct electricity) contains free ions.
For an electrical circuit to be complete, there's got to be a flow of electrons
Electrolysis reactions involve oxidation and reduction
Oxidation is loss, reeducation is gain
When common salt is dissolved in water and electrolysed it produces 3 useful products hydrogen, chloride, sodium hydroxide