2016 AQA Chemistry C2 - Unofficial Mark Scheme 2016

Better to use nano particles instead of powder as a catalyst because of nanotubes have larger surface area to volume ratio

In the Electrolysis question what was the gas that was produced at the negative electrode is is Oxygen or Hydrogen?
I wrote Oxygen then crossed it out and wrote Hydrogen is it right?

I wrote it doesn't have any delocalised electrons?? Would that get any marks

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I'm not sure I wrote about ions because it's quite familiar that water has ions but idk whether the mark scheme will accept it? It could do though

They could do the experiment at 5 degrees Celsius by putting the conical flask in a water bath heated at 5 degrees Celsius.

It was ions because water does not have free electrons but in mineral water the ions of calcium, magnesium, sodium etc can carry the charge but they are not present in pure water.

I put place a lid on beaker to reduce heat loss for the apparatus/more accurate question... Opinions?

Am I the only one that didnt find it that easy? Im a triple student and I found C3 easier

Same. I made a few stupid mistakes on here which I could have easily avoided. I found c3 slightly easier, especially the last 5 marker.

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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? 7
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. Values between 200kg and 300kg would all probably be accepted. The examinors want to see that you can compare values on all graphs and find one which suits them all. Doing this should get you most of the marks.
3. Question on Particles and Nano Particles
Why are nano particles good catalysts? They have a large surface area to volume ratio.
Put the dots/crosses in the diagram to resemble electrons. Put 2 dots/crosses in the overlapping bits and 6 outside of it. There should be 8 in the outer shell of oxygen so getting them in the wrong places but drawing 8 dots/crosses should get you 1 mark out of 2.

4. Reaction experiment (cross under flask)
Why did the liquid go cloudy? Sulfur was produced (see equation) which dissolved in the water.
What should she keep the same? The amounts of each substance used. The person looking at the cross.
How could she do it with a temperature of 5 degrees? Cool the liquid
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
How does copper conduct electricity? It has free electrons in its structure which can flow through when a current is applied.
Why is diamond very hard to break? Diamond is hard because it has lots of strong covalent bonds which are hard to break.
Why would you use thermosetting polymers in pan handles? They are strong and heat resistant. They have a high melting point.Note: The question parts may not be in the right order.If you did the B2 exam on Friday, we have the mark scheme for that as well!

3. How does the size of nanoparticles compare to the size of regular particles?
Much, much smaller (1-100nm across).

Then u stupid. "Ammonium chloride" was written on that page and it was basic copying.



U grade for you, matey

for 1d- if you said use an insulating beaker to help reduce heat loss would you get the marks or is that wrong?

I thought it said how does it compare to the size of an atom, in which case the nano particles are bigger as they contain roughly a few hundred atoms

3. How does the size of nanoparticles compare to the size of regular particles?
Much, much smaller (1-100nm across).