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The big giant AQA CHEM5 thread!!! (May/June 2013)

Reply 180

popnit

14

Original post by Sherlockedd

Ohhh sorry :L I LOVED CHEM 4 OMG I MISS IT SO MUCH :frown:

it's okay! haha it is good. What did you get in it?

Reply 181

Sherlockedd

14

Original post by popnit

it's okay! haha it is good. What did you get in it?

I love Chem 4 and I got 104/120 :smile:

I'm super stressy about Chem 5 though, the past papers are horrible :frown:

Reply 182

dizzy17

Does anyone know how to do question 6di) on the june 2012 paper?

Reply 183

sikhtank27

2

Original post by dizzy17

Does anyone know how to do question 6di) on the june 2012 paper?

Yeah i'm having trouble with answering 6 (d) all together its the only one on the paper i cant answer correctly

Reply 184

Minnie me

Original post by dizzy17

Does anyone know how to do question 6di) on the june 2012 paper?

for question 6di) the one marker we are given these equations

[MnO4]- +8H+ +5e- ----> Mn2+ +4H2OO

Fe2+ -------> Fe3+ + e-

[C2O4]2- -----> 2CO2 + 2e-

and we asked to find the ratio of FeC2O4 : MnO4-

1st we combine the last two equations to give FeC2O4

2nd we combine this new equation with the first one to find the ratio

Spoiler

Reply 185

Zazuwaved

10

hellow... can somebody please explain to me (in layman's terms) what atomic radius actually means?

Reply 186

Vip3rgt9

10

Original post by Zazuwaved

hellow... can somebody please explain to me (in layman's terms) what atomic radius actually means?

The distance between the centre of the nucleus and the outermost electron "orbiting" it.

Reply 187

Minnie me

Original post by sikhtank27

Yeah i'm having trouble with answering 6 (d) all together its the only one on the paper i cant answer correctly

hi i have posted a reply to 6di) and i'll 6dii) now

we are asked to calculate the % of FeC204 H20 in the original sample

we are given this in the question:

FeC2O4H2O (impure) made a total of 250cm3, but used 25cm3
mass :1.381g
volume: 25cm3

and MnO4-
volume: 22.35cm3
concentration: 0.0193 moldm-3
so
1st we will calculate the moles of MnO4- using n=(cv)/1000

2nd we use the molar ratio (we found this in 6di) to calculate the moles of FeC2O4H2O

3rd we know moles of FeC2O4H2O in 25cm3 but we need to know the moles of FeC2O4H2O in 250cm3

4th we can calculate the mass of FeC2O4H2O using the m=(n mr) formula

5th to calculate the % we use the formula (actual/theoretical)100

P.S actual is the ans to the 4th step and theoretical is the mass given in question

and there you have it the answer to question 6dii , if you need any more help just ask

me :biggrin:

(edited 11 years ago)

Reply 188

Zazuwaved

10

Original post by Vip3rgt9

The distance between the centre of the nucleus and the outermost electron "orbiting" it.

Thank you very much :biggrin:

Reply 189

Vip3rgt9

10

Original post by Zazuwaved

Thank you very much :biggrin:

No problem, happy to help :smile:

Reply 190

evan almighty

5

Original post by sikhtank27

Who's layman?

Layman is just a word used to represent someone that doesn't have any knowledge of technical words in a specific subject. So she just meant explain it simply and without using technical words.

Posted from TSR Mobile

Reply 191

Zazuwaved

10

Original post by evan almighty

Layman is just a word used to represent someone that doesn't have any knowledge of technical words in a specific subject. So she just meant explain it simply and without using technical words.

Posted from TSR Mobile

Thank you very much :colondollar:

Reply 192

evan almighty

5

Original post by Zazuwaved

Thank you very much :colondollar:

I apologise…I didn't mean anything by it! :colondollar:

Or did I

Posted from TSR Mobile

Reply 193

Zazuwaved

10

Original post by evan almighty

I apologise…I didn't mean anything by it! :colondollar:

Or did I

Posted from TSR Mobile

Haha

Posted from TSR Mobile

Reply 194

sikhtank27

2

Original post by Minnie me

hi i have posted a reply to 6di) and i'll 6dii) now

we are asked to calculate the % of FeC204 H20 in the original sample

we are given this in the question:

FeC2O4H2O (impure) made a total of 250cm3, but used 25cm3
mass :1.381g
volume: 25cm3

and MnO4-
volume: 22.35cm3
concentration: 0.0193 moldm-3
so
1st we will calculate the moles of MnO4- using n=(cv)/1000

2nd we use the molar ratio (we found this in 6di) to calculate the moles of FeC2O4H2O

3rd we know moles of FeC2O4H2O in 25cm3 but we need to know the moles of FeC2O4H2O in 250cm3

4th we can calculate the mass of FeC2O4H2O using the m=(n mr) formula

5th to calculate the % we use the formula (actual/theoretical)100

P.S actual is the ans to the 4th step and theoretical is the mass given in question

and there you have it the answer to question 6dii , if you need any more help just ask

me :biggrin:

That helped alot thanks!!!

Reply 195

Minnie me

Original post by sikhtank27

That helped alot thanks!!!