2016 AQA Chemistry C2 - Unofficial Mark Scheme 2016

I thought the pH for the neutral solution was 7 not 0 😂 0 would be very acidic...

Reply 61

krystal16

For 1d on how to make the results more accurate, i put insulation to prevent heat from the environment altering the temperature of the solution because it was an endothermic reaction, is that wrong?

Reply 62

guy321

11

Original post by SkyeAmber

What one did you all put for the one where you ticked a box? I ticked the third box which was a guess? And for the one where you had to finish the half equation near the end?

I ticked the first. H+ makes a solution acidic and OH- makes a solution alkaline.

Reply 63

username2303857

13

a neutral pH is 7 not 0.

Reply 64

hello654321

16

would it be ok to say insulate the cup to prevent energy loss so the thermometer readings are accurate? *because there is no energy transfers

Reply 65

Original post by SkyeAmber

What one did you all put for the one where you ticked a box? I ticked the third box which was a guess? And for the one where you had to finish the half equation near the end?

i ticked the first box which im 99% sure is correct and for the half equation i just guessed it by writing 2's in the blank space

Reply 66

GCSE_core

2

Wasn't the percentage mass one 14/17 * 100= 82.35 not just 82?

Reply 67

Original post by epage

a neutral pH is 7 not 0.

Truss me bruv, i was like why the hell did the guy write 0 ahhahaaaahaha

Reply 68

Original post by GCSE_core

Wasn't the percentage mass one 14/17 * 100= 82.35 not just 82?

init thats what i wrote

Reply 69

dh12345

7

Original post by Naco88

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.

This mark scheme is not official and was made purely from what we saw in the exam.

AQA B2 Higher - Unofficial Mark Scheme (Updated Regularly) (Should have the last few questions of foundation)

Note: Not all the questions are complete

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)
Why did the liquid go cloudy? Sulfur was produced (see equation) which dissolved in the water.
What should she keep the same?
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.

Predicted grade boundaries will come soon.

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

Sulfur doesn't dissolve in the water it is insoluble

Reply 70

Frankie___

Will I still get the marks if I said the answer was 82.35%? I wrote next to it to 2 d.p.

Reply 71

GCSE_core

2

Original post by imforcedtosignup

init thats what i wrote

You reckon it'll still get the mark?

i got this too?

Original post by Naco88

x

The pH one is 7 not 0 :smile:

Was the one about nanoparticles in relation to atoms on this exam? I put that nanoparticles are 'of the order of a few hundred atoms' and 'bigger than atoms' because that's what it says on the spec (the first bit, anyway!)

I put that she should keep the concentration of the acid the same and the volume of the solution the same for 4. :smile:

And there was a question that asked for the gas that would form at the negative electrode in the second electrolysis experiment; I think the answer was hydrogen.

What did people put for a change to the experiment to measure rate of reaction at 5 degrees? (I think that was this one, I'm so confused between C2 and 3!)

Reply 74

SkyeAmber

2

Does anyone know how many marks it'll be for a C out of all 3 papers combined?

Reply 75

CaptErin

5

Original post by Frankie___

Will I still get the marks if I said the answer was 82.35%? I wrote next to it to 2 d.p.

They usually say in the mark scheme like:
'82.4%' and then on the side say, 'allow 82%/82.35241...'
So rounding to any decimal place would be fine (I put the same :smile:

)

Reply 76

ajs12

7

Original post by krystal16

For 1d on how to make the results more accurate, i put insulation to prevent heat from the environment altering the temperature of the solution because it was an endothermic reaction, is that wrong?

I put that, accuracy is how close it is to the "true value", I gathered that if heat transfers took place, the ultimate temp. would not be close to the "true value". Everyone seems sure about on digital thermometers etc. though idk, at least someone else wrote something similar XD

Reply 77

Everydaygent

Original post by GCSE_core

Wasn't the percentage mass one 14/17 * 100= 82.35 not just 82?

This true. Although normally the examiner will allow for rounding up or down to 82/83.

Its best to stick with what you and I wrote. 82.35% as in some cases theyll only accept rounding to one decimal place ie. 82.4%

Reply 78

Arcaddia

5

Original post by CaptErin

The pH one is 7 not 0 :smile:

Was the one about nanoparticles in relation to atoms on this exam? I put that nanoparticles are 'of the order of a few hundred atoms' and 'bigger than atoms' because that's what it says on the spec (the first bit, anyway!)

I put that she should keep the concentration of the acid the same and the volume of the solution the same for 4. :smile:

And there was a question that asked for the gas that would form at the negative electrode in the second electrolysis experiment; I think the answer was hydrogen.

What did people put for a change to the experiment to measure rate of reaction at 5 degrees? (I think that was this one, I'm so confused between C2 and 3!)

THE GAS IS HYDROGEN?! Lol i totally guessed that if that's right!

Reply 79