2f sulphur and nitrogen. allotropes of sulphur sulphur molecule consists of 8 atoms in a ring form
TRANSCRIPT
2f Sulphur and Nitrogen
Allotropes of sulphur
Sulphur molecule consists of 8 atoms in a ring form.
Allotropes of sulphur
It melts at 115°C (low) which is because of its simple molecular structure.
Allotropes of sulphur
At first the sulphur is very runny because of the weak bonds between the sulphur molecules (intramolecular bonds)
Allotropes of sulphur
As it is heated more strongly, the rings break and join together to make long chains. It becomes sticky.
Allotropes of sulphur
Near to the boiling point, the chains start to break, the liquid is less viscous and it starts to evaporate.
Allotropes of sulphur
When it evaporates it forms S2 molecules (like O2 which is also group 6)
Allotropes of sulphur
If it is poured quickly into water, plastic sulphur is made.It is “frozen” in long chain molecules like rubber.
Allotropes of sulphur
It will eventually change back into S8.
Nitrogen
• Extracted from air by fractional distillation
• If air is cooled down, at -183°C oxygen condenses into a liquid and then at -196°C Nitrogen condenses too.
Nitrogen
Nitrogen is generally an unreactive gas, and needs fairly extreme conditions to get it to react with oxygen
Its inert nature is used to help preserve food.
Ammonia NH3
Ammonia NH3
Ammonia NH3
• Only common alkaline gas Only common alkaline gas.
• EASILY dissolves in water
• Turns damp litmus paper blue.
Laboratory preparation of NH3
• Heat solid ammonium chloride with solid calcium hydroxide
Ammonia + acids
• Ammonia (an alkali) reats with acids to form salts
NH3 + HNO3 NH4NO3
Ammonium (NH4+) salts
• Ammonium nitrate – NH4NO3
• Ammonium sulphate – (NH4)2SO4
• Ammonium chloride – NH4Cl