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

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

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

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

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)

The answer is equal


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Hm

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


Posted from TSR Mobile

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.

Hope that's made it clear

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!


Posted from TSR Mobile

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.

Hope that's made it clear

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!


Posted from TSR Mobile

Hi is there any chance you could send me a link of the practical booklet that AQA released. Thanks.

Do we need to know redox titrations and iodometric titrations?

can anyone help with part b?

As far as I know we need redox titrations as its an assessed practical.