Chemistry Paper 2: Blind Spot Part 1

The title is quite aggravating.

So a few more days and we are going to have our P2 chemistry. Though not as difficult as its P1, still it poses a lot of challenge, especially if we want score higher.

Some points to remember is that the questions here are divided into several parts. What I mean is that each questions will usually correspond with one of the major topics in chemistry. So for a better mark, always skip the part that you feel incapable (example: organic chemistry) to do and search through the part that you are confident with (example: thermodynamic), don't waste time doing it linearly. Strange thing is that organic chemistry always seems to appear while the other parts comes out randomly (serious). So a good strategy is that to master your organic chemistry.

I bold "usually" with a reason. The setters may elaborate two topics in one question (periodic table and chemical bonding) or perhaps split one topic in two questions (isomerism and organic chemistry reactions). Study all parts, no matter what.

Some topics that resurges back are the electrolysis, atomic structure and chemical bonding.

Inorganic chemistry had become a frequent topic lately (periodic table, group II, group VII).

The topic that keeps freaking people is the nucleophile and electrophile; especially their reactions and how to differentiate them. Their mechanism, fortunately, is easily memorized once we know which is which.

When asked about electrolysis, the most common format of the question is:
(-) Draw a diagram and describe the electrolysis of bla, bla, blah
(-) Reaction at cathode and anode
(-) The products and their uses

To answer the first part, you can only memorize the diagram that we have learned, namely for the extraction of aluminum from aluminum oxide, electrolysis of brine and purification of copper. Note that we do not need to draw sophisticated diagram, a simple one will do.


This is a simple diagram for the extraction of aluminium.


And this is the picture for the electrolysis of brine. Do not forget to draw the diaphragm!

To determine the reaction at cathode or anode, all we have to do is to determine the cation (positive ion) and anion (negative ion). This is the important point. Cathode is the negative pole whilst anode is the positive pole. Therefore reaction at cathode involves cation (positive ion) while reaction at anode involves anion (negative ion).

The products for each electrolysis are aluminum (extraction of aluminum, duh), sodium hydroxide, chlorine and hydrogen gas (electolysis of brine) and copper (purification of copper). I suppose I don't need to discuss their uses because most textbooks had already discussed them and if you can't find them in textbook, Google is everybody's best friend (or Yahoo maybe).