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# AQA AS Chemistry 7404/1 and 7404/2 - 27th May 2016 and 10th June 2016 watch

1. (Original post by youngson)
Once you have the total number of moles of gas which is 5 (3+2), to find the number of moles of B2O3, just divide by 5 which should give a value of around 0.04038
Ah okay! That makes sense, i read it wrong! I thought it meant carbon and chlorine.
Thank you!
2. (Original post by monoman)
The moles of gases formed is 5. The moles of boron oxide is 1. Therefore, it is a 1:5 ratio. Therefore, you divide by 5
Thank you!!
3. (Original post by Turtlebunny)
Yeah, its most likely our grade boundaries will go down because its a new spec and its meant to be harder, but unfortunately your boundaries will probably go up since everyone whos doing it is an A2 student so they'll all be good at it
I wish you luck tomorrow
Same to you

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4. Need some help pleased on 1b
I don't understand the question

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5. (Original post by Bloom77)
Need some help pleased on 1b
I don't understand the question

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The number of molecules in one mole of NH3 is avogadro's constant multiplied by 1. However, to get the number of particles, you have muliply this answer by 4 as there are four atoms in NH3 (one nitrogen and 3 hydrogen)
6. (Original post by monoman)
The number of molecules in one mole of NH3 is avogadro's constant multiplied by 1. However, to get the number of particles, you have muliply this answer by 4 as there are four atoms in NH3 (one nitrogen and 3 hydrogen)

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7. (Original post by Bloom77)

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Hm
8. (Original post by monoman)
Hm

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9. One mole of a substance always contains Avogadro's constant number of particles
10. Who's ready for tomorrow !!!
11. (Original post by Bloom77)
Need some help pleased on 1b
I don't understand the question

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Hi, so the number of moles is the same as Avogadro's number right?

You have the same number of atoms in a mole as the number of MOLECULES in a mole.

Therefore you have Avogadro's number of argon atoms, and Avogadro's number of NH3 molecules.

Good luck to everyone tomorrow, the specifications were very nasty, and our teachers set the grade boundaries for that as 65% for an A, 55% for a B etc. the mark schemes were also overly harsh and normally would be more lenient. I think tomorrow is the slightly easier one personally, just make sure you learn the equations for the reduction of H2so4 using halide ions, uses of chlorine, and the reactions between group 2 and sulphuric acid and water.

AqA have also released a practical booklet, which includes things for A level, but has all of our core practicals in, as well as working out percentage uncertainty but idk if this is online, I'll have a look.

Good luck tomorrow!

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12. (Original post by Christina1999H)
Hi, so the number of moles is the same as Avogadro's number right?

You have the same number of atoms in a mole as the number of MOLECULES in a mole.

Therefore you have Avogadro's number of argon atoms, and Avogadro's number of NH3 molecules.

Good luck to everyone tomorrow, the specifications were very nasty, and our teachers set the grade boundaries for that as 65% for an A, 55% for a B etc. the mark schemes were also overly harsh and normally would be more lenient. I think tomorrow is the slightly easier one personally, just make sure you learn the equations for the reduction of H2so4 using halide ions, uses of chlorine, and the reactions between group 2 and sulphuric acid and water.

AqA have also released a practical booklet, which includes things for A level, but has all of our core practicals in, as well as working out percentage uncertainty but idk if this is online, I'll have a look.

Good luck tomorrow!

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Hi is there any chance you could send me a link of the practical booklet that AQA released. Thanks.
13. (Original post by Christina1999H)
Hi, so the number of moles is the same as Avogadro's number right?

You have the same number of atoms in a mole as the number of MOLECULES in a mole.

Therefore you have Avogadro's number of argon atoms, and Avogadro's number of NH3 molecules.

Good luck to everyone tomorrow, the specifications were very nasty, and our teachers set the grade boundaries for that as 65% for an A, 55% for a B etc. the mark schemes were also overly harsh and normally would be more lenient. I think tomorrow is the slightly easier one personally, just make sure you learn the equations for the reduction of H2so4 using halide ions, uses of chlorine, and the reactions between group 2 and sulphuric acid and water.

AqA have also released a practical booklet, which includes things for A level, but has all of our core practicals in, as well as working out percentage uncertainty but idk if this is online, I'll have a look.

Good luck tomorrow!

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Thank you
That makes so much sense
And I'm a retake student as well! Argh! I should've known that!
Thank you!
Good luck to you too!

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14. (Original post by Zeed.)
Hi is there any chance you could send me a link of the practical booklet that AQA released. Thanks.
This is the whole booklet..my teacher cut it down and printed it for us with only our AS practicals in, but the first practical (volumetric solution) is on page 64. Sorry I cant send you a digital copy of my version!

http://filestore.aqa.org.uk/resource...-7405-PHBK.PDF
15. any predictions for tomorrow
16. Do we need to know redox titrations and iodometric titrations?

17. can anyone help with part b?
18. (Original post by rosemondtan)
Do we need to know redox titrations and iodometric titrations?
As far as I know we need redox titrations as its an assessed practical.
19. (Original post by nicoledsk)

can anyone help with part b?
Just multiply the I- equation by 5 and combine so you can eliminate the electrons on both sides of the equation
20. (Original post by Paper_souls)
As far as I know we need redox titrations as its an assessed practical.
I thought redox titrations were A2? Like using KMnO4 and all that?

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