AQA GCSE Chemistry - C2 & C3 (14th May 2015)

In case anyone might find it useful, I did a practice answer on electroplating earlier today:

Explain how and why a copper cup would be electroplated with silver.

The cup would act as the negative electrode, and the positive electrode should be a block of pure silver metal. The electrolyte used needs to be an ionic substance containing ions of the plating metal (silver). For example, silver nitrate solution could be used. It is important that the electrolyte is in solution so that the ions can move to carry charge. The silver ions in the electrolyte will move to the negative electrode (the cup) because they are positively charged. Here each silver ion will gain 3 electrons and be reduced to silver atoms, hence the cup will be plated with silver metal. The silver metal at the negative electrode is required to top up the solution with silver ions. Electroplating is done to coat the surface of one metal with another. In this case, it is done for decoration, to make the cup look nice, because making a pure silver cup would be too expensive.

Would anyone add anything else? Thanks

Really good answer. How many marks was this question worth?

My predictions for B2 are:
- almost definitely a question on thermosetting/softening polymers, because it hasn't come up in the past four years
- the 6 marker is unlikely to be a method to do with producing salts, because the B2 six marker was a method (my money is on structure of macromolecules but I'm unsure)
- hopefully nothing on nano particles because there was a large-ish section on them last year

praying for a good one!

Could anyone give me a simple method on titration. My head is killing because I cannot understand anything to do with it. Pleeease help me!!

nanoparticles have a larger surface area to volume ratio than normal particles - 1-100nm
objects that comprise of nanoparticles are harder and stronger
nanoparticles react faster due to the fact that they have a higher surface area meaning that there are more exposed particles and less locked in particles within the article itself that aren't reacting as they are not exposed.
nanotubes - are semiconductors, if thy ask why they are lubriactive then say that their structure is very similar to that of graphite meaning that the layers can slide over eachother due to the fact that that there are weak bonds between the layers.

Anyone struggling use this - https://m.youtube.com/watch?list=PLhzZT1_v76sA1yQYHFASlOENdHDMSa4hs&v=hlSQq1TgMUY MASSIVE HELP along side your revision book (although it says C he covers everything)

If anyone would like to use these online flashcards, they are available

Unit 2: https://s.tudy.it/uihh9
Unit 3: https://s.tudy.it/qps72

In case anyone might find it useful, I did a practice answer on electroplating earlier today:

Explain how and why a copper cup would be electroplated with silver.

The cup would act as the negative electrode, and the positive electrode should be a block of pure silver metal. The electrolyte used needs to be an ionic substance containing ions of the plating metal (silver). For example, silver nitrate solution could be used. It is important that the electrolyte is in solution so that the ions can move to carry charge. The silver ions in the electrolyte will move to the negative electrode (the cup) because they are positively charged. Here each silver ion will gain 3 electrons and be reduced to silver atoms, hence the cup will be plated with silver metal.The silver metal at the negative electrode is required to top up the solution with silver ions. Electroplating is done to coat the surface of one metal with another. In this case, it is done for decoration, to make the cup look nice, because making a pure silver cup would be too expensive.

Would anyone add anything else? Thanks

Don't you mean positive? Also, isn't the positive electrode impure?

This is different to purification of a metal. In purification, the impure metal is the positive electrode and the pure is negative.

In electroplating (which is slightly different), the plating metal (e.g gold or silver) is the positive electrode, and the object to be plated (e.g a spoon) is the negative electrode.

Don't you mean positive? Also, isn't the positive electrode impure?

Could any one explain me how to do he empirical formula? Am really strugling with this😣

haha yes I did sorry about that! Um no I'm pretty sure pure or solution would be contaminated, that's what the revision guide says anyway

Alright, just making sure! My revision guide says impure, not sure why.