AQA GCSE Chemistry exam June 2015 - OFFICIAL THREAD

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Jay Rye
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Here's a thread were you can post any queries, questions and predictions as to wash will come up.

Personally, I'm hopping the 6 marker will be the lime cycle because I find that easy
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Cookies15
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What do you need to know for the limestone cycle?
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spnlove
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(Original post by Cookies15)
What do you need to know for the limestone cycle?
- Limestone is Calcium Carbonate

The Limestone Cycle
- When heated it thermally decomposes to make Calcium Oxide and CO2
- Calcium Oxide then reacts with water to produce Calcium Hydroxide (You need to know that Calcium hydroxide is alkali and can be used to neutralise acidic soils)
- If you add carbon dioxide to calcium hydroxide it turns back into Calcium Carbonate (Limestone) and water

Making things from limestone
- Powdered limestone is heated in a kiln with powdered clay to make cement
- Cement + sand + water = mortar (Mortar is used to stick bricks together)
- Cement + sand + aggregate = concrete

Advantages and Disadvantages of quarrying limestone

Advantages: 1) Can make useful materials e.g. dyes, paints and roads
2) Used in power stations to neutralise sulfur dioxide
3) Quarrying provides jobs and brings money into economy leading to local improvements in transport, roads e.t.c
4) Once quarrying is done, restoration of land usually happens anyway

Disadvantage: 1) Makes huge, ugly holes
2) Creates lots of noise and dust ( so do cement factories)
3) Destroys habitats of wildlife
4) Limestone needs to be transported, causes more pollution
5) Waste produces tips
6) Energy needed likely to come from burning fossil fuels (causes pollution)

Qualities of Limestone products

- Limestone widely available, cheap, easy to cut
- More hard-wearing but still attractive
- Concrete can be poured into moulds, quick and cheap way to make buildings but they're unattractive
- Limestone, concrete and cement don't rot when they get wet, don't get eaten by insects & are fire-resistant
- Concrete doesn't corrode but relatively low tensile strength & can crack
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soccerdude007
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They might ask us about the evidence for wegener's theory of continental drift.
Any chance of Miller Urey coming up?
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GCSE_core
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Hi, could someone please explain to me how fermentation is done to produce ethanol? I know the equation, but would like a greater understand if the process. Thankyou.


Also, if asked any question on an emulsifier/emulsions would this be adiquate:

Emulsions are liquids in which the oil and water mix. This is due to an emulsifier being added. An emulsifier has two ends, a hydrophilic head attracted to water, and a hydrophobic tail which repells water.
In an emulsion, the hydrophobic end pushes its way into the oil, where's the hydrophilic end stays on the water surface. This enables the oil droplets to stay as oil, and water to stay as water.

Thankyou 😊
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Ellie and Gracie
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(Original post by GCSE_core)
Hi, could someone please explain to me how fermentation is done to produce ethanol? I know the equation, but would like a greater understand if the process. Thankyou.


Also, if asked any question on an emulsifier/emulsions would this be adiquate:

Emulsions are liquids in which the oil and water mix. This is due to an emulsifier being added. An emulsifier has two ends, a hydrophilic head attracted to water, and a hydrophobic tail which repells water.
In an emulsion, the hydrophobic end pushes its way into the oil, where's the hydrophilic end stays on the water surface. This enables the oil droplets to stay as oil, and water to stay as water.

Thankyou 😊
That would be good, however an emulsion doesn't mix until an emulsifier is added. An emulsion is when oil doesn't dissolve in water, and sits ontop. Don't say mix because in the mark scheme this is ignored, the word you need is dissolve😊
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GCSE_core
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(Original post by Ellie and Gracie)
That would be good, however an emulsion doesn't mix until an emulsifier is added. An emulsion is when oil doesn't dissolve in water, and sits ontop. Don't say mix because in the mark scheme this is ignored, the word you need is dissolve😊
Thankyou for the advice! Good luck with your exams if you have any!😊
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Ellie and Gracie
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(Original post by GCSE_core)
Thankyou for the advice! Good luck with your exams if you have any!😊
No problem glad to help😊and yeah I am doing gcse core science so have chemistry on Tuesday and dreading it!
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GCSE_core
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(Original post by Ellie and Gracie)
No problem glad to help😊and yeah I am doing gcse core science so have chemistry on Tuesday and dreading it!
Chemistry is my weakest by far! How did you find the biology? 😊
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Ellie and Gracie
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(Original post by GCSE_core)
Chemistry is my weakest by far! How did you find the biology? 😊
Agreed! And yeah it was okay thanks yours? Although there was a lot of data analysing and I found that really hard
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TheAlphaParticle
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Is this C1?
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ARON911
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Any ideas what the grade boundaries will be for Foundation paper? Same as last year??
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Just4
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(Original post by TheAlphaParticle)
Is this C1?
Yah
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ARON911
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Im doing foundation paper for all 3 sciences, if i get a C in Biology and 2 high Ds in Chem/physics. Would my over all grade be a C? And Ive also done the practical back in November. And my teacher said my result was pretty good in the exam. Apparently the practical cuts as 25% towards the GCSE. How does that work??? Thanks.
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Ellie and Gracie
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Any ideas on what might come up?
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GCSE_core
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(Original post by Ellie and Gracie)
Agreed! And yeah it was okay thanks yours? Although there was a lot of data analysing and I found that really hard
I found it hard with all the data analysing, didn't quite finish paper. Looking at unofficial Mark scheme think I only got 27 which is just a b usually so I'll just have to see in the summer!
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Young Sinatra
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I got an A* in the ISA so what grades should I get in B1, C1 and P1 to get an overall grade of an A or a B
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Young Sinatra
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(Original post by GCSE_core)
I found it hard with all the data analysing, didn't quite finish paper. Looking at unofficial Mark scheme think I only got 27 which is just a b usually so I'll just have to see in the summer!
i got around the same
I hope they do bring the grade boundaries down because I think a lot of people didn't expect so much analysing of data and got them wrong (like me)
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soccerdude007
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Any Chance of Miller Urey coming up?
I personally think that alot on metals will come up this year
They could ask us about the Evolution of the atmosphere- possibly as a 6 marker
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soccerdude007
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I reckon alot on metals will come up this year
There's gonna be quite a few balancing equations- knowing AQA and their sneaky questions
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