The teacher did not go through in detail the practical parts of unit 4 and 5. I did some past papers recently and im scoring around 50%
Besides the transition metal ion colors, copper chemistry, chromium chemistry, and organic synthesis, i don't know what else will come up. Help. and this exam is coming in 3 weeks.
anyone? Im really stressed about it...
these are some practical techniques you need to know about (meaning be able to draw their diagrams, describe them, plus explain why certain aspects are like the way that they are)
- steam distillation (used in u5 when you're making an aryl amine)
- solvent extraction (also used when you're making an aryl amine)
- suction filtration (just a faster form of filtration that produces a drier solid, and is used for soluble impurities)
- how to find the melting point/boiling point of a substance (btw when a substance is impure it's boiling point goes up & its melting point lowers)
- paper chromatography for amino acids
- thin layer chromatography
- reflux (why would you use reflux... drawing the diagram of how the apparatus is used including its condenser the right way round)
- how to measure the volume of a gas product(the syringe method connected to the conical flask is an accurate method)
- Know how to make a standard solution (pipette 25cm/3 of the solution into a graduated flask of 250cm/3 & then fill it to the mark using water)
- Review all of organic chemistry (including arenes). You need this for tests like Brady's reagent, the iodoform reaction, aldehydes reaction with Benedict's or Fehling's (same result)/Tollen's reagent. Esterification is an important process that you should go over too.
- Go over general large processes, such as: making paracetamol, making a phenylamine - in depth. Also, the nitration of benzene comes up & nitrous acid reacting with phenylamines. (they usually require other substances to make the reactants - know what these substances are)
-Testing for alcohols & carboxylic acids. (First PCL5, then if you're trying to find out if its the carboxylic acid use an acid test like adding sodium hydrogencarbonate)
- That being said revise the amines chapter.
-Hazard signs (flammable, oxidising, corrosive etc..)
- The kinetics chapter comes up, with questions asking you to determine the order with respect to reactants. So review all of that.
- Equilibrium (I'm not sure about acid equilibrium, pretty sure its not in this unit), more the Kc, how to write the equation - remember square brackets etc.. why you might ignore the volume when working it out ( the moles are the same on both sides, so it cancels out, therefore, you don't need it)
-The flame tests, which is AS knowledge.
-Redox chemistry should be revised as there have been past papers where they want you to calculate the E of the cell and evaluate the set up when you're measuring the emf. (E.g the student might be using the wrong material for the electrode, the concentration of the electrolyte isn't 1dm/3 etc.. I'd advise going over this chapter altogether)
- Review NMR spectroscopy. It's quite important as most papers include a question about it. (low resolution & high-resolution NMR should be revised)
- Just like AS Unit 3, you're going to need to know how to test for ions. Not just metal ions, anions like Chloride, Bromide, Iodide... Sulphate... Carbonate... Thiosulfate.../ the test for gases Hydrogen... Oxygen... Carbon dioxide (& the apparatus to carry out this particular test)... Ammonia (React with HCl to give you white fumes)... Chlorine...
- Bromine's reaction with phenylamine & phenols (you get a white ppt)
- Also, sometimes they sneak in a question about colours of metal chlorides like NiCl4(yellow) or CuCl4(also yellow) or CuCl3(green) or CoCl4 (blue)
- Drying a substance, you use a drying agent such as magnesium sulfate.
- How you should read a meniscus (from the bottom/base of the meniscus) & what happens if you read it from the top ... you end up exerting less of the volume you need
Listen, I find this unit quite difficult too & I'm still struggling lol. I'd recommend doing past papers in combination with studying. Obviously, focus on actually learning the content - but see what things you're missing on when doing past papers. The mark schemes will give you the exact answer they want & you should learn from that.
Good luck bro.
Forgot to mention, there are good threads on studentroom, just search 'chemistry unit 6 studentroom' on google & it'll give you the results you need + students provide good resources.