For me the B123 exam and C123 exam are exactly one month apart, so lots of revision time. We have done a lot in class. The B123 practice papers had only like 70%+ for an A* so if they are the same for the other exams then I should be able to get an A* easily, as on all the practice papers I've been getting A*s and dropping only like 3/4 marks. However the way UMS works means that this means nothing as far as I can see it.
The topics I am least certain on include:
Minerals in the Earth etc.
Atmospheric evolution
Polymers
The rest is just exam technique really. I don't think I need to do that much revision but I'm trying to do 1/2 an hour each day at least.
Practice questions for anyone who cares
1) Explain the different methods of obtaining salt and the uses that they are most suited to. (6)
2) Complete the following chemical equation:
Methane + Oxygen = __________ + _________
CH4 + 2O2 = __________ + _________
(3)
3) Match up the cause of an atmospheric change and the gas(es) it changed. Each cause and/or gas may have more than one line.
Volcanoes Nitrogen
Green plants Oxygen
Carbon Dioxide
(3)
4) State two ways that polymers can be changed and the properties that this affects.
Change 1 ________
Properties affected _____________________________________________________-
Change 2_________
Properties affected _____________________________________________________
(4)
5) When brine is electroysed, three products are formed. List them.
1___________
2___________
3___________
(3)
My answers (may be wrong)
1) Solution mining can be used to obtain salt. This entails pumping water into a salt deposit and then using the resultant brine as and when needed. It is suited to the chemical industry as the salt is relatively pure but has health risks attached to it. Salt mining can also be used to obtain salt. This entails using machinery to dig salt out of underground deposits. This is suited to use as rock salt or grit as the salt contains many impurities so cannot be used in the chemical or food industries. Finally, evaporating seawater can be used to obtain salt. This is suited to the food industry as the salt obtained is very pure.
2) = Water + Carbon dioxide
= 2H2O + CO2
3) Volcanoes -> Nitrogen, Carbon Dioxide
Plants -> Carbon Dioxide, Oxygen
4) Plasticization
It reduces forces between polymers, lowering their boiling point and making them more flexible.
Cross-linking
It chemicularly bonds polymer chains, increasing their boiling point, increasing forces between them and making them stronger.
5)Sodium Hydroxide
Hydrogen
Chlorine