Chem 問題 Plz help～

1.
The iron nail dissolves in the acid to give a yellowish-brown solution.
2Fe + 6H2SO4 → Fe2(SO4)3 + 3SO2 + 6H2O

2.
Ammonia is slightly ionized in water to give OH-(aq).
NH3 + H2O ≒ NH4+ + OH-
The OH- can hydrolysis the oil/grease to give soap. The soap can be easily removed by water, and soap can help to remove oil/grease by emulsification.
(The equation and details of the hydrolysis of oil/grease are not included the CE syllabus.)

3.
Nitric acid is produced in industry by Ostwald Process. The starting material is ammonia, which is produced in Haber Process. The ammonia is firstly oxidized by oxygen in air at 900oC, in the presence of platinum catalyst. The reaction is exothermic, and the temperature can be maintained without heating once the reaction starts.
4NH3 + 5O2 → 4NO + 6H2O
NO gas is cooled to 30oC, and then react with oxygen in air to give NO2 gas.
2NO + O2 → 2NO2
Nitric acid is formed when the NO2 is dissolved in water in the presence of oxygen in air.
4NO2 + 2H2O + O2 → 4HNO3

4.
In the presence of the enzyme from micro-organisms, ethanol in wine is oxidized to ethanoic acid, which is sour in taste.
CH3CH2OH + O2 → CH3COOH + H2O

5.
Sulphur CANNOT be reduced by aqueous sodium sulphite.
Chlorine CAN be reduced by aqueous sodium sulphite.
Cl2 + SO32- + H2O → 2Cl- + SO42- + 2H+

6.
KMnO4 is stored in dark. Otherwise, KMnO4 will be decomposed in light to give MnO2 and O2.
(The equation and the details of the decomposition of KMnO4 in light are out the CE syllabus.)

7.
Pipette filler is used to help a pipette to withdraw liquids/solutions. If pipette filler is not used, you would use your mouth. It is dangerous.

8.
Collection over water is the best method to collect gases which are insoluble in water. The method is suitable for all insoluble gases. Since the gaseous products in cracking (mainly small alkenes) are insoluble in water, they are collected over water.