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Chemistry OCR B 10/06/16 Unofficial Markscheme

Since no one else has started one, either message me or reply to the thread with answers if you've got any with the question number
1.E
2. F and C
3. C8H18
4. Single bond between carbon atoms, in brackets with lines extending outwards, n outside brackets, two fluorine atoms for each carbon

5. Esters have an oxygen atom(s)

? Six marker -
-Carbon Cycle Explained
-Growing population means overcrowding, therefore deforestation, more carbon dioxide
-Growing population means more fossil fuels burnt as energy demand increases, more CO2.

? Goretex is waterproof and breathable because :
-Polyurethane membrane has pores small enough to keep water droplets out
-Big enough to let water vapour/perspiration escape

?Haber Process Six marker-
-Best line was the 350 degrees celcius one, would help to mention it achieved a 70 percent yield
-Higher temperature decreases percentage yield, however it increases rate of reaction therefore companies use a higher temperature to make ammonia faster
- Higher pressure increases percentage yield but increases manufacturing plant costs, therefore a lesser pressure is used

? Wegners Theory
- Accepted because it explains a wide range of evidence - eg Sea Floor Spreading
-Has been discussed and tested by many scientists

?Aluminium Oxide Balanced Equation :
4Al + 3O₂ --> 2Al₂O₃

? Amalgam - Mercury
Copper and Zinc - Brass
Solder - Lead and Tin

? Iron + Water + Oxygen - Hydrated Iron Oxide

?Alloy A is the best choice

?Aluminium does not rust/corrode in moist air therefore Metal A

? Pottasium Hydroxide + Nitric Acid - Pottasium Nitrate + Water

? Fertiliser needs to be dissolved because plants only take in nutrients through the roots

? Eutrophication :
-Phosphates and nitrate level of water increased, creates algae bloom on surface
-Sunlight cannot reach oxygen producing plants on sea bed, these die
-Aerobic bacteria use up oxygen whilst feeding on dead matter which reduces oxygen level
-Most organism which respire die

? Chromatography Six Marker
-the plant has to be crushed to break the cell walls
- then boiled and dissolved in a suitable solvent.
- Chromatography can then be used to extract the substance, (not sure if you had to explain the process of chromatography or not)

-Impurities altered the boiling point slightly
-Something about the chromatography paper

? Concentration:
-Higher concentration means particles are more closely packed
-This means that frequency of collisions are increased
-Faster rate of reaction

?Why is it diiffcult to develop safe to Use Medecines : (Any three)
- Trials to determine adverse effects/ and to get rid of them
- Difficulty obtaining and isolating compounds needed
-Needs to be completed before patents expire
-Needs to be tested on living tissue

? Volume when iron and zinc added together:
60cm3

? 16,000 x2 + 32,000J energy released
? 32,000 = 100 x 4.2 x T 100 x 4.2= 420, 32,000/420 = 76.2

? Rate of reaction was 1.46 recurring, you had to work out the gradient

(edited 7 years ago)

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Reply 1

samuelfairbrass

Question 1: E
Question 2: C and F

Reply 2

samuelfairbrass

On the 6 mark question (last) I wrote about impurities altering the boiling point slightly, the two dots on the chromatography showed 2 chemicals instead of 1- showing that there is one chemical other than the desired sample present. I also wrote that Phil must crush the leaves, filter them and evaporate them

Reply 3

soph.browne

What alloy did people choose for the plane? I chose C but most of my friends chose A. But A was high cost so??

Reply 4

EzraCrowley

This was the answer to the question at the bottom of the first page, might've been (1)(d), not sure :-/

Reply 5

EzraCrowley

Original post by soph.browne

What alloy did people choose for the plane? I chose C but most of my friends chose A. But A was high cost so??

I said A because it wasn't dense (so light enough to fly) but strong. The price was a disadvantage but there'd be no use having a very dense material to make plane wings, even if it was cheap, because it wouldn't fly...

I could be wrong but most people seem to agree... sorry

Reply 6

EzraCrowley

Original post by samuelfairbrass

I had no idea on the chromatography bit but that sounds right. For extracting drugs from the plant, according to the official ocr revision app it says "the plant has to be crushed then boiled and dissolved in a suitable solvent. Chromatography can then be used to extract the substance you want", which I paraphrased in the exam. There may be other techniques though; I don't think we were even taught it in class tbqh!

I put the same about boiling points, so that's good :smile:

Reply 7

samuelfairbrass

I got alloy A because it was high strength and low density so it was light so more fuel efficient -- for the plane question

Reply 8

McMartinski_

Original post by anonymous290

Since no one else has started one, either message me or reply to the thread with answers if you've got any with the question number

2. F and ?
3. C8H18
4. Single bond between carbon atoms, in brackets with lines extending outwards, n outside brackets, two fluorine atoms for each carbon
5. Esters have an oxygen atom(s)

? Six marker -
-Carbon Cycle Explained
-Growing population means overcrowding, therefore deforestation, more carbon dioxide
-Growing population means more fossil fuels burnt as energy demand increases, more CO2.

? Goretex is waterproof and breathable because :
-Polyurethane membrane has pores small enough to keep water droplets out
-Big enough to let water vapour/perspiration escape

? Amalgam - Mercury
Copper and Zinc - Brass
Solder - Lead and Tin

? Iron + Water + Oxygen - Hydrated Iron Oxide

? Pottasium Hydroxide + Nitric Acid - Pottasium Nitrate + Water

? Eutrophication :
-Phosphates and nitrate level of water increased, creates algae bloom on surface
-Sunlight cannot reach oxygen producing plants on sea bed, these die
-Aerobic bacteria use up oxygen whilst feeding on dead matter which reduces oxygen level
-Most organism which respire die

? 16,000 x2 + 32,000J energy released
? 32,000 = 100 x 4.2 x T 100 x 4.2= 420, 32,000/420 = 76.2

Damn I might have actually done well in chemistry for once...

Reply 9

anonymous290

Thanks guys I was watching a movie XD, i'll update it now

Reply 10

nivibilla

The answers for the one where it asked you to find the cm^3 released if both iron and zinc were used was 60CM^3 right?
56/2 + 64/2 = 60

/2 as it was 0.015g of each and the data was given in 0.3g for each.

Reply 11

Vanilla Cupcake

Original post by nivibilla

did you have to calculate it? i just wrote 60 bc it was right in between the total volumes for zinc and iron

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Reply 12

anonymous290

Original post by nivibilla

Hi nivi,

I dont really know, I added the total volumes for both together so i got 120, but I think thats wrong

(edited 7 years ago)

Reply 13

Chittesh14

http://www.thestudentroom.co.uk/showthread.php?t=4155873&p=65644257#post65644257

Can you please tell me what the actual question for the Haber Process 6 marker was, I think I read it wrong :'(

Reply 14

Vanilla Cupcake

Original post by Chittesh14

http://www.thestudentroom.co.uk/showthread.php?t=4155873&p=65644257#post65644257

Can you please tell me what the actual question for the Haber Process 6 marker was, I think I read it wrong :'(

it gave you a graph with pressure on the x axis and yield on the y axis, then the curved lines were temperature - so it was comparing an increase/decrease in pressure/temperature and how this affects the yield

the actual question asked you to identify the conditions needed for the highest yield of 70%, then asked you to explain why manufacturers don't use these conditions (and i guess the conditions they use instead)

Posted from TSR Mobile

Reply 15

anonymous290

Original post by Chittesh14

http://www.thestudentroom.co.uk/showthread.php?t=4155873&p=65644257#post65644257

Can you please tell me what the actual question for the Haber Process 6 marker was, I think I read it wrong :'(

The most I can remember was that there were four lines on the graph, one at 350 degrees celcius and the rest were higher. The the graph showed percentage yield and 350 had was the line at the top.

It asked which result has the highest percentage yield or something like that
Then it said explain why these conditions are not used in the Haber Process normally

Reply 16

nivibilla

Yeah cos it said 0.015g so you had to add them up and then divide by 2.

You can't get double the amount of h2 if the mass stays the same.

So the ans is 60.

Posted from TSR Mobile

Reply 17

nivibilla

Yeah that is bacically the calculation. But you just did it visually.

This is for @vanilla cupcake

Posted from TSR Mobile

(edited 7 years ago)

Reply 18

Chittesh14

Original post by Vanilla Cupcake

xPosted from TSR Mobile

Original post by anonymous290

Thanks guys, I guess I read the question wrong.
I still answered in partially correct - I talked about how they use the conditions that give the most economical yield. Idk what I read - but I read why they don't aim for the highest percentage yield lol. Got the first part right and second wrong :/ should get 3/6 hopefully