***2015 LC Chemistry - Higher Level - June 16th***

135083

Did anyone else find that tough? Think I did better in the mocks!

MmmPancakes

That was pretty difficult

ImRebecca

135083 wrote: »

Did anyone else find that tough? Think I did better in the mocks!

I thought it was the worst chemistry test I ever did! Kissed my A1 goodbye

Chocolalla

I loved ittttttttti

12hello345

That was so hard worst exam ever was hoping for A definitely only managed a C , ffs I hate the sec

dazzadazza

I thought the questions were asked in an awkward way. For example instead of asking for the trends across and down a group they asked for bigger and smaller atoms.

I still felt like I gave everything a decent shot. I'm thinking B1 A2.

dazzadazza

Chocolalla wrote: »

I loved ittttttttti

Do you reckon you got that A1?

blue_velvet

Could anyone do the formation of ethanol question?I couldn't get the right equation for combustion of ethanol

Noire

Pretty hard paper, all the experiment questions were pretty tricky imo

dazzadazza

blue_velvet wrote: »

Could anyone do the formation of ethanol question?I couldn't get the right equation for combustion of ethanol

I think it was C2H5OH + 3O2 ---> 2CO2 + 3H2O

Chocolalla

dazzadazza wrote: »

Do you reckon you got that A1?

I hope re , u ??

135083

Hopefully still got the A1, but didn't like the paper at all. Was less of a "throw down everything you know off by heart paper" and moreso one where you had to really work them out IMO. What did you guys do for the equilibrium question, multiply Kc by 10 then solve the quadratic?

dazzadazza

Chocolalla wrote: »

I hope re , u ??

Not too sure about an A1 because there were a few parts where I relied on waffle. I'll settle for an A2 B1 though.

MmmPancakes

135083 wrote: »

Hopefully still got the A1, but didn't like the paper at all. Was less of a "throw down everything you know off by heart paper" and moreso one where you had to really work them out IMO. What did you guys do for the equilibrium question, multiply Kc by 10 then solve the quadratic?

Yeah, what did you get for 'x'? I think I got like 15.32 or something

The_N4sir

That was a harder paper than I thought it would be. Was going for an A1 but i would be happy with a A2/B1 on that paper.

Anyone else get 20 for the x value in question 11? Cant remember exactky but was a nice whole number

Chocolalla

What talk get for the value oh heat of formation ??

The_N4sir

Chocolalla wrote: »

What talk get for the value oh heat of formation ??

Around -270 kJ/mol

Blue giant

It could have been worse was my first thought. Roughly added up my marks at the end of the exam and I reckon I got a B1/B2. I'm just happy to be finished

blue_velvet

dazzadazza wrote: »

I think it was C2H5OH + 3O2 ---> 2CO2 + 3H2O

I had that! Just couldn't get the question to work out

Alex Meier

MmmPancakes wrote: »

Yeah, what did you get for 'x'? I think I got like 15.32 or something

X = 20

Number of gaseous moles = 5 mol/L or 50 mol/10L

Ima_mokster

Worst paper ive seen in terms of wording, was hoping for a definite A1, I'll take an A2 now tbh.. anyone know the initial appearance of phenylmethanol before KMNO4^-1? Paper was much like what I heard about the biology in that it wasn't as accessible as previously imo

OMGeary

Alex Meier wrote: »

X = 20

Number of gaseous moles = 5 mol/L or 50 mol/10L

Think thats right. I got x to be 2 because I divided by 10, and got 5 overall

Deranged96

Hard but not cruel.

I know of two calculations I messed up already

But sure be grand

expiiplus1

Why would you multiply by 10 in the equilibrium problem? I'm really nervous about that part of the paper.
My reasoning was that the only thing that could affect Kc was temperature and that remained the same...

Bah_Humbug

kindof crying, never not gotton an A1 in chemistry and then BAM

Iamtheduchess

No A1, more like a C1. So disappointed!
Thankfully had gone over catalysts etc!

MmmPancakes

Can someone do the solution to that equillibrium question?

Doctorhopeful

The_N4sir wrote: »

That was a harder paper than I thought it would be. Was going for an A1 but i would be happy with a A2/B1 on that paper.

Anyone else get 20 for the x value in question 11? Cant remember exactky but was a nice whole number

I got about 12ish, i saw how the quadratic would be 20/60 but the equation didn't work out so i had to use the quadratic formula. Is x=20 would you not have gotten a negative figure for A as A was 30 -2x at equil??

Ima_mokster

Im pretty sure x=10?

Doctorhopeful

Hard exam, the way they asked for stuff was really convoluted sometimes. Did 9 Qs but did them well, still think i'm on track for an A, whether it's an A1 or A2 depends on the marking scheme i think. Glad it's over. The experiments were perfect btw, did all three!

The_N4sir

Doctorhopeful wrote: »

I got about 12ish, i saw how the quadratic would be 20/60 but the equation didn't work out so i had to use the quadratic formula. Is x=20 would you not have gotten a negative figure for A as A was 30 -2x at equil??

I took A as 30-x so I guess i'll have to see what others got

blue_velvet

What was the percentage yield for benzoic acid?I think I got around 43%

Doctorhopeful

The_N4sir wrote: »

I took A as 30-x so I guess i'll have to see what others got

Ah **** i did X for both idk which is right... probably why it didn't work out so cleanly....

OMGeary

Doctorhopeful wrote: »

I got about 12ish, i saw how the quadratic would be 20/60 but the equation didn't work out so i had to use the quadratic formula. Is x=20 would you not have gotten a negative figure for A as A was 30 -2x at equil??

No it wouldn't be minus 2 as they were all in the same ratio

Fiona G

Whyyy do I look at these threads? Already seeing mistakes I made. Yet I'll still continue to read the thread...:p

Was an okay paper. Bit trickier than other years in that there was a lot of reasoning to do instead of learned off stuff. Can't really predict my grade at all tbh. I loved the short questions and the rates question.

The_N4sir

Doctorhopeful wrote: »

Ah **** i did X for both idk which is right... probably why it didn't work out so cleanly....

You should still get a lot of the marks for the calculation anyway

Doctorhopeful

blue_velvet wrote: »

What was the percentage yield for benzoic acid?I think I got around 43%

I got 42.42% without rounding during the Q so i imagine anywhere around 42-43 is right

The_N4sir

Doctorhopeful wrote: »

I got 42.42% without rounding during the Q so i imagine anywhere around 42-43 is right

I definitely got that wrong I got around 60%:P
Not having the equation threw me off for that part

DexterXX

I got 50 overall for the equilibrium gas question. What did ye say for the effect of an increase in storage temperature on pressure?

Chocolalla

The_N4sir wrote: »

Around -270 kJ/mol

Got that as well

AlfaJack

DexterXX wrote: »

What did ye say for the effect of an increase in storage temperature on pressure?

Increase in temperature favours the forwards reacting and the forwards reaction produces the greater number of moles so the pressure would increase? That's what I said anyways...

Doctorhopeful

The_N4sir wrote: »

I definitely got that wrong I got around 60%:P
Not having the equation threw me off for that part

Yeah that was indicative of how the paper was oddly worded! You had to read in the question that it was 1:1 took me ages to realise

Seanh966

Doctorhopeful wrote: »

Yeah that was indicative of how the paper was oddly worded! You had to read in the question that it was 1:1 took me ages to realise

Pretty confident answer was 56 or 57% , several A1 candidates in my class got this

Dingle123

Seanh966 wrote: »

Pretty confident answer was 56 or 57% , several A1 candidates in my class got this

I got about 57% aswell

Kerrypike

Dingle123 wrote: »

I got about 57% aswell

How was it supposed to be done?

Chickennuggets

In the equilibrium question I got x=9.135. Any one esle get that

The_N4sir

Yeah I think the answer is 57 good few in my class got that

Seanh966

Kerrypike wrote: »

How was it supposed to be done?

Grams of phenylmethanol Divided by molecular mass of phenylmethanol to get number of moles, ratio is one is to one so multiply this number by the molecular mass of benzoic acid for theoretical yield, put actual yield over theoretical for percentage yield

Chickennuggets

Kerrypike wrote: »

How was it supposed to be done?

N = 6.35all over 108 (mr ) = 0.026 0.026 X 122(mr of benzoic acid ) = 3.172 1.83 all over 3.172 x100 = 57٪

Thebabyjesus

Got 57.7% for percentage, what did people get for grams pf crystalised sodium thiasulfate?

Kerrypike

Oh right I see.. I just used grams dang it