Presence of UV light.
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List the conditions for catalytic cracking of long chain alkanes.
- Temp 600 deg C
- Catalyst: aluminium oxide or silicon (IV) oxide
Write down the general formula for: alkanes, alkenes, alcohols, carboxylic acids.
Alkane: CnH2n+2
Alkene: CnH2n
Alcohol: CnH2n+1OH
Carboxylic acid: CnH2n+1COOH
List the percentage composition of air.
- Nitrogen (78%)
- Oxygen (21%)
- Carbon dioxide (0.03%)
- Noble gases (less than 1%, mainly argon)
- Water vapour (variable)
Explain, using structure and bonding, why silicon dioxide has high melting and boiling point.
Silicon dioxide has a giant molecular structure, consisting of a large number of silicon and oxygen atoms covalently bonded to form a big tetrahedral structure. A lot of energy is needed to break the strong covalent bonds, resulting in the high melting point and boiling point of silicon dioxide.
Describe the test for nitrate ions.
Add aqueous sodium hydroxide and aluminium foil into a sample of the solution, and warm gently. If a pungent colorless gas is produced, which turns damp red litmus blue, it shows the presence of nitrate ions.
Describe the test for hydrogen gas.
Insert a lighted splint into a test tube of the gas. If the lighted splint is extinguished with a ‘pop’ sound, it shows the presence of hydrogen gas.
Describe the test for Cu2+ ions using aqueous sodium hydroxide.
Add a few drops of aqueous sodium hydroxide into a sample of the solution, followed by adding aqueous sodium hydroxide in excess. If a blue precipitate forms which is insoluble in excess of aqueous sodium hydroxide, it shows the presence of Cu2+ ions.
Define electromagnetic induction.
Electromagnetic Induction is a process in which an electromotive force (e.m.f.) is induced in any conductor whenever there is a change in the magnetic flux linkages through the conductor.
Define induced magnetism.
Induced magnetism occurs when a magnetic material is placed near to, or touching, any pole of a permanent magnet, thereby becoming an induced magnet itself.
Once removed from permanent magnet, induced magnet will lose its magnetism.