***2013 LC Chemistry Before/After***

MarieCurie22

yoppo wrote: »

it was: 200 x Mol I2/1 = 9.4 x .02/2

Because it's 2:1 (said in ques), divide answer above by 2 to get moles/L

Then x32 to get g/L
Then x1000 to get mg/L
Thats your answer in ppm

Ii just did V1M1 N1 using different N1s for Oxygen again i was just wondering...and wbu the flaw in q2?

TheChosenOne

yoppo wrote: »

it was: 200 x Mol I2/1 = 9.4 x .02/2

Because it's 2:1 (said in ques), divide answer above by 2 to get moles/L

Then x32 to get g/L
Then x1000 to get mg/L
Thats your answer in ppm

Wait wait, so I2 is simple calculation, no dividing by two, and you divide by two only in part (i) which asks for Oxygen, right?

woopah92

MarieCurie22 wrote: »

Is it ok for q 5 when dealing with bohrs theory being modified to talk about the exsistance of sublevels??

I think they were looking for the electrons move in a wave motion not in a fixed orbit like Bohr thought.
Not sure sublevels would be right, could be though you never know with the marking scheme.

MarieCurie22

woopah92 wrote: »

I think they were looking for the electrons move in a wave motion not in a fixed orbit like Bohr thought.
Not sure sublevels would be right, could be though you never know with the marking scheme.

it said one other....which suggests there was more than one answer....

Glee_GG

MarieCurie22 wrote: »

Is it ok for q 5 when dealing with bohrs theory being modified to talk about the exsistance of sublevels??

The fact that it didn't account for orbitals and sub-levels is a valid point.

woopah92

yoppo wrote: »

A) Definition
Polystyrene
C) More accurate, bases cause the tap to stick
D) Use digital thermometer and use a lid to minimize heat loss
E) Basic calculation
F) Corrosive, burn your skin. Triangle symbol with the test tube and hand.

The last time it was asked, digital thermometer wasn't accepted as full marks #justsaying

TheChosenOne

Where are those college people who just write out the solutions to every question? XD

xJEx

woopah92 wrote: »

I think they were looking for the electrons move in a wave motion not in a fixed orbit like Bohr thought.
Not sure sublevels would be right, could be though you never know with the marking scheme.

Yeah you can say it didnt explain the discovery of subelevels! There'es loads of reasons.. I just said only worked well for hydrogen and not for atoms with more than 1 electron

weirdspider

KildareKing wrote: »

same and I put an arrow pointing towards it and wrote "this is hand"

Loool describing those symbols is so funny. I was like "hand with test tube dropping liquid"

yoppo

TheChosenOne wrote: »

Wait wait, so I2 is simple calculation, no dividing by two, and you divide by two only in part (i) which asks for Oxygen, right?

I did divide by two. I said that above! Sure it's a 2:1 ratio!

yoppo

MarieCurie22 wrote: »

Ii just did V1M1 N1 using different N1s for Oxygen again i was just wondering...and wbu the flaw in q2?

I said the steam valve should be in the water and also they should have included a steam trap.

yoppo

TheChosenOne wrote: »

Where are those college people who just write out the solutions to every question? XD

That would be me! Yoppo BSc (Chemistry) Hons circa 2008.

MarieCurie22

yoppo wrote: »

That would be me! Yoppo BSc (Chemistry) Hons circa 2008.

wait what you have a degree and sat the paper today?

yoppo

MarieCurie22 wrote: »

wait what you have a degree and sat the paper today?

Yip. Doing my Leaving again! Last time I done it was 2003 :pac:

MarieCurie22

yoppo wrote: »

Yip. Doing my Leaving again! Last time I done it was 2003 :pac:

you crazycrazy person!!!!!!!! why!!!?

MarieCurie22

what other subjects are you doing?

yoppo

MarieCurie22 wrote: »

you crazycrazy person!!!!!!!! why!!!?

Because I only got a 2:2 in my degree and want to do med. Can't do grad med with it. I needed a 2:1 but missed out by 2%....

Biology, Physics, Farming, Home Ec, Hons Maths, Pass English.

Physics, farming and Hons Maths are new.

Hamza Malik

Did 9 questions questions 1, 4, 5 and 6 were great

The mechanism question was good too

Q 2 and 9 and 8 were iffy

And I also did question 3 in the end which was ok. Hopefully I got a B1 or even an A2. One can dream.

yoppo

For question 8 it said reagent not condition so hopefully they will take HCL and UV Light!

Hazardous Garden Of Eden

These are my answers to the calculation questions, hopefully they ring a bell :P

Q1(f)
Concentration of I2 = 4.7x10^-4 mol/L
(i) Concentration of O2 = 2.35x10^-4 mol/L
(ii) 7.52x10^-3 g/L
(iii) 7.52 ppm

Q3(e)
Heat produced = 4.342 kJ
Heat of reaction = -57.89 kJ/mol

Q4(c)
How many neutrons = 4.8x10^22

Q6(c)
Heat change = -126.4 kJ/mol

Q9(c)
Kc = 123

Q10(b)(ii)
Mass of aluminium = 346.75 g
Mass of Aluminium Oxide = 1032.75 g

Q10(c)(iv)
Fraction of mass = 1/8

Q11(b)
pH = 11.278

MarieCurie22

Hazardous Garden Of Eden wrote: »

These are my answers to the calculation questions, hopefully they ring a bell :P

Q1(f)
Concentration of I2 = 4.7x10^-4 mol/L
(i) Concentration of O2 = 2.35x10^-4 mol/L
(ii) 7.52x10^-3 g/L
(iii) 7.52 ppm

Q3(e)
Heat produced = 4.342 kJ
Heat of reaction = -57.89 kJ/mol

Q4(c)
How many neutrons = 4.8x10^22

Q6(c)
Heat change = -126.4 kJ/mol

Q9(c)
Kc = 123

Q10(b)(ii)
Mass of aluminium = 346.75 g
Mass of Aluminium Oxide = 1032.75 g

Q10(c)(iv)
Fraction of mass = 1/8

Q11(b)
pH = 11.278

Are you sure about all these?

mocker2012

Hazardous Garden Of Eden wrote: »

These are my answers to the calculation questions, hopefully they ring a bell :P

Q1(f)
Concentration of I2 = 4.7x10^-4 mol/L
(i) Concentration of O2 = 2.35x10^-4 mol/L
(ii) 7.52x10^-3 g/L
(iii) 7.52 ppm

Q3(e)
Heat produced = 4.342 kJ
Heat of reaction = -57.89 kJ/mol

Q4(c)
How many neutrons = 4.8x10^22

Q6(c)
Heat change = -126.4 kJ/mol

Q9(c)
Kc = 123

Q10(b)(ii)
Mass of aluminium = 346.75 g
Mass of Aluminium Oxide = 1032.75 g

Q10(c)(iv)
Fraction of mass = 1/8

Q11(b)
pH = 11.278

I got the same answers as far as i can remember!!

xJEx

I don't think the aluminium one is right there - more like 432g and 816g

yoppo

MarieCurie22 wrote: »

Are you sure about all these?

Q6, 10c and 11 are right. I changed the temperature for the specific heat capacity to kelvin so I made a slip there (thank you physics!)....

MarieCurie22

xJEx wrote: »

I don't think the aluminium one is right there - more like 432g and 816g

Thats what i got too

Hazardous Garden Of Eden

MarieCurie22 wrote: »

Are you sure about all these?

The 10(b) ones I'm not sure cos I did them in a hurry towards the end of the exam, but the others I think (I hope) I'm right!

wow exuberant

yoppo wrote: »

Q6, 10c and 11 are right. I changed the temperature for the specific heat capacity to kelvin so I made a slip there (thank you physics!)....

I don't think the kc value is right

xJEx

Yoppo how did you find physics ? )

SecondMan

xJEx wrote: »

I don't think the aluminium one is right there - more like 432g and 816g

Same

Nl90

I'm so mad at myself !
I did all my calculations wrong!
PH , Kc , and winkler method!
Couldn't focus at all
Had some mistakes in ex2
Do you think I might get a B2 ?!