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2016 AQA GCSE Chemistry Unofficial mark scheme 2016

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Reply 20

onychair

You get best look with onychair, and look fantastic in your group.

Reply 21

SmithAmelia

Original post by ScienceFantatic

Question 1
nucleus( 1 mark)
( +1), electrons( -1), neutron is uncharged( 3 marks)

Not in form 2,8,8, has 1,8Boron has 10 electrons, the structure had 9 electrons( 3 marks)

Question 2
Tick box: copper oxide

20.3(2 marks)

Digital thermometer, more precise and not subject to human error(2)

Carbon particles produced( particulates)Insufficient oxygen or incomplete combustion(2)

Best fuel because it produces least smoke/ burns the most cleanly. Produces the most energy per g(2)

Question 3
Advantages of hydrogen
Only product water
Renewable
Provides more energy
No co2 or s02 released

Disadvantages
Hydrogen is explosive
Hard to store because it is a gas
From natural gas( methane which is a greenhouse gas)
Engines need to be converted( 6 marks)

Thermal decomposition(1)

Question on potassium carbonate: doesn't fully thermally decompose, co2 not released, Bunsen burner temperature is not high enough( 3 marks)

Reactivity question: (2 marks)

Question 4:
Conditions for cracking: high temperatures and a hot catalyst(2)

Fermentation question: sugar is dissolved and yeast is added to make ethanol(2)

Ethanol question: ethene is reacted with steam at high temperatures and catalyst(2)

Advantages and disadvantages of crude oil vs plants: Crude oil is a continuous process so faster, crude oil is more widely available, crude oil more reliable and things are set up for crude oil fractions

Non renewable, co2( global warming), SO2

(4 marks)

Question 5
metal ores are ores which contain enough of the metal to be worthwhile extracting( 1 mark)

It is converted to steel because cast iron is brittle or to make it stronger
Steel has more uses( 2 marks)

2Fe2O3+ 3C = 4Fe+ 3CO2( 2 marks)

It is not sent to landfill because this takes up space and causes pollution
It is not reused as it might have lost its strength and become unstable( 3 marks)

Didn't the question for landfill and recycle ask to give three reasons why it is reused? So shouldn't it be because it's cheaper than extracting from new ores, saves resources etc

Reply 22

username1888141

Original post by ScienceFantatic

Was that definitely question 5?

Yes because it was the last question as there were only 5 questions altogether.

Reply 23

chocolatewheel

For the structure of Z could you have said protons and neutrons instead of the nucleus and for cracking conditions if you just said catalyst and not a hot catalyst would that still count
Grade boundary predictions?

Reply 24

Resty

1st question I believe it asked for you to describe the components of the nucleus only, as well as there sub atomic charges so an answer would be

The nucleus is comprised of Neutrons and Protons: the charge of a proton is +1, the charge of a neutron is 0 and the overall charge of the nucleus is positive.

Reply 25

toms4242

Question 2c could also be:
Add insulation to the beaker so less heat is lost meaning the final temperature of the water is more accurate.

Reply 26

thecomputernerd

last question (5marks)
reaction with hydrogen in a presence of a nickel catalyst at 60 degrees, hardened so it is solid at room temperature and not liquid at room temperature, and hydrogenated oils are useful as spreads in cakes, have high melting points,

Reply 27

TheConfusedMedic

can steel be hammered into shape whereas cast iron cannot? I didn't know what to put for the 2nd mark :s-smilie:

Reply 28

loshaw20

Original post by ScienceFantatic

Question 1
nucleus( 1 mark)
( +1), electrons( -1), neutron is uncharged( 3 marks)

Not in form 2,8,8, has 1,8Boron has 10 electrons, the structure had 9 electrons( 3 marks)

Question 2
Tick box: copper oxide

20.3(2 marks)

Digital thermometer, more precise and not subject to human error(2)

Carbon particles produced( particulates)Insufficient oxygen or incomplete combustion(2)

Best fuel because it produces least smoke/ burns the most cleanly. Produces the most energy per g(2)

Question 3
Advantages of hydrogen
Only product water
Renewable
Provides more energy
No co2 or s02 released

Disadvantages
Hydrogen is explosive
Hard to store because it is a gas
From natural gas( methane which is a greenhouse gas)
Engines need to be converted( 6 marks)

Thermal decomposition(1)

Question on potassium carbonate: doesn't fully thermally decompose, co2 not released, Bunsen burner temperature is not high enough( 3 marks)

Reactivity question: (2 marks)

Question 4:
Conditions for cracking: high temperatures and a hot catalyst(2)

Fermentation question: sugar is dissolved and yeast is added to make ethanol(2)

Ethanol question: ethene is reacted with steam at high temperatures and catalyst(2)

Advantages and disadvantages of crude oil vs plants: Crude oil is a continuous process so faster, crude oil is more widely available, crude oil more reliable and things are set up for crude oil fractions

Non renewable, co2( global warming), SO2

(4 marks)

Question 5
metal ores are ores which contain enough of the metal to be worthwhile extracting( 1 mark)

It is converted to steel because cast iron is brittle or to make it stronger
Steel has more uses
Corrosion resistant
( 2 marks)

2Fe2O3+ 3C = 4Fe+ 3CO2( 2 marks)

It is not sent to landfill because this takes up space and causes pollution
It is not reused as it might have lost its strength and become unstable( 3 marks)

For the question about the burning food . I said that the beaker should be insulated so that less heat is lost to the surroundings by conduction . Would that be right ?
Also for the question about why potassium carbonate doesn't turn limewater cloudy , I said that it doesn't thermally decompose because it's BP is not reached and this is shown by the fact that no mass is lost and therefore no co2 produced .

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Reply 29

username1888141

Original post by Resty

oh so the third mark was saying the nucleus was positively charged.
do you think i'll get three marks for saying protons are +1 charged (postive) and neutrons are 0 charged (neutral)?

Original post by Resty

In pretty sure it was just sub atomic particles of boron and relative charges

Reply 32

loshaw20

Original post by lunaticash19995

oh so the third mark was saying the nucleus was positively charged.
do you think i'll get three marks for saying protons are +1 charged (postive) and neutrons are 0 charged (neutral)?

Yeh same I named the sub atomic particles and stated their charges but could not work out which info was needed for the third mark 🙄🙄

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Reply 33

LogicalFallacy

Original post by SmithAmelia

Didn't the question for landfill and recycle ask to give three reasons why it is reused? So shouldn't it be because it's cheaper than extracting from new ores, saves resources etc

It was recycled, not reused. It couldn't be reused because of metal fatigue, right?

Reply 34

TheConfusedMedic

and do you think you had to include a disadvantage of reusing materials? I listed 3 disadvantages of landfill or something :s-smilie:

Reply 35

username1888141

Original post by ScienceFantatic

In pretty sure it was just sub atomic particles of boron and relative charges

No i believe it was talking about z which was the nucleus

Reply 36

a_homida

Original post by ScienceFantatic

Question 1
nucleus( 1 mark)
( +1), electrons( -1), neutron is uncharged( 3 marks)

Do you think i'd get the mark for saying protons are positive and neutrons are neutral?

(edited 7 years ago)

Reply 37

M451

Last question:

React with hydrogen, nickel catalyst, 60 degrees c
Done to increase melting point so it's more solid at room temp and can be used as margarine spreads