2016 AQA Chemistry C2 - Unofficial Mark Scheme 2016

Okay so for the why is it cloudy question I wrote precipitate at first but then wrote about precipitation, would I still get the mark? and also, for the change question I wrote a stopwatch?

I think it was ammonium chloride rather than aluminium chloride. I think the question was what salt is formed when ammonia and hydrochloric acid react together. Also, on the nanoparticle question, it asked about the size of nanoparticles in relation to atoms so I put that atoms are smaller than nanoparticles as well as that nanoparticles have a diameter of 1-100nm. I think you're right about the surface area bit though.

For the question about the magnesium chloride did people talk about ionic boding?

Poll: I accidentally set the poll to only display results when it has ended (in 7 days), I am trying to fix this.

Hello. Welcome to my AQA Chemistry C2 Unofficial mark scheme! Due to the success of my other mark scheme for AQA Biology which got 40k views I will happily do another and look forward to seeing how you guys found the exam.

This mark scheme is made completely by people who have done the exam so is written purely from knowledge. We will try and get the questions in the right order however putting marks next to each is very hard so please do not request this. If you remember a question we forgot then feel free to comment it below or contact me on twitter (@NacoRBLX) and I will be sure to add it.1. Question on Temperature Change
a) 5.75 (do not include the anomaly)
b)
c)
d) How could you change the apparatus to get more accurate results? Use a digital thermometer. It is more accurate.
2. Question on Fertilisers
What is the PH after being neutralized? 0
Percentage by mass: 14+1+1+1 = 17 (14/17) x 100 = 82%
6 Mark Question about a farmer using ammonium nitrate on his crops. The best value to use was around 200kg because the lowest possible amount went into nearby lakes and it produced the maximum profit.

3. Question on Particles and Nano Particles
Why are nano particles good catalysts?
They have a large surface area to volume ratio.
4. Reaction experiment (cross under flask)

5. Question on electrolysis (Magnesium Chloride)
Why do the molecules need to be melted or dissolved in water?
The particles need to be able to move so they can get to the electrodes. This also separates them.
Why does magnesium form at the negative electrode?
It is M²⁺ so it will be attracted to the negative electrode. It will then gain 2 electrons and therefore no longer be an ion.
In experiment 2, magnesium did not form at the negative electrode, why?
The magnesium chloride was dissolved in water so hydrogen atoms are present. These are less reactive than magnesium so will form.
6. Question on materials
a)
b) Diamond is hard because it has lots of strong covalent bonds which are hard to break.
c) Note: The question parts may not be in the right order.

This is a mix of my answers and those of the community but they are not guaranteed to be correct.


If you did the B2 exam on Friday, we have the mark scheme for that as well!
http://www.thestudentroom.co.uk/showthread.php?t=4155717

Everyone is getting carried away. An A will be like 45!

For the one about improving the apparatus, I put about using a lid to reduce heat loss? Is that correct?

For the 2 variables I said to keep constant the volume of sodium thiosulfate and hydrochloric acid is this right?

What is the PH after being neutralized? 0
it is not zero is 7
because 0 is a PH of acids but 7 is neutral

I put that too