**Chemistry...Before/After

RedTexan

Dicksboro_man wrote: »

got totally different ans for those. 0.12 m/L and 4.38 g/L

i could be wrong though

Got that too

TMCGY

Dicksboro_man wrote: »

got totally different ans for those. 0.12 m/L and 4.38 g/L

i could be wrong though

I got that too

dmca93

^^
I got your answers too, I didn't divide because it was mol/l and g/l!

reznov

I scribbled out but-1-ene accidentally. Got a Kc of 704. Concentration reduces due to iodine forming a complex with starch.

Fantastic paper.

finality

Saracarroll wrote: »

This doesn't matter as it is only the conc that was changed

It does matter. If the HCl were in excess the new graph would level off at the same height as the old one. But as it's limiting, it'll level off at half the height of the old one.

TMCGY

Why is a pipette filler used?

diarmo06

Great paper, pity that shorts and atomic theory were probably the hardest ones on the paper tho. Everyone still did them no doubt.

leaveiton

Feck, forgot to call it but-1-ene, just called it butene Does it matter?

dmca93

For the pipette filler I said for accurecy and so you wouldn't suck up the solution....anyone else?

dmca93

I'd say they'll accept butene

paddyhes

Got the last part of Q2 wrong cause forgot about the yield and got 9.8 for Kc value
Hopefully still do well though..

jos360

TMCGY wrote: »

Why is a pipette filler used?

dmca93 wrote: »

For the pipette filler I said for accurecy and so you wouldn't suck up the solution....anyone else?

My friends mam did science in TCD and they used to manually suck the liquid into pipettes ...

Hermione Granger

Cosmic.Postman wrote: »

I got 8, pretty sure that was right.

Same:D

Mista

dmca93 wrote: »

For the pipette filler I said for accurecy and so you wouldn't suck up the solution....anyone else?

Only accurate way to fill a pipette.. thats all :P

Dicksboro_man

i think the ans to the non-volatile liquid one was that we won't be able to measure the exact temp of the gas as the liquid will have a bp above that of water and in our calculations for volatile liquid we assume the temp of hot gas is the same as temp of boiling water?

and i also got 58.5 amu for rel atomic mass


What did we all say why PH3 bonding is different to the rest of the molecules?

leaveiton

For the pipette filler I just said "It sucks the liquid into the pipette and ensures accuracy" :P

finality

I gave like 5 really obvious reasons for using a pipette filler, didn't know what they'd accept :L

hollingr

Dicksboro_man wrote: »

got totally different ans for those. 0.12 m/L and 4.38 g/L

i could be wrong though

I could be wrong also, I thought a lot of my answers seemed like fairly unreasonable figures.

For the ones I got wrong, I'd say I will still get most of the marks though, so I think my grade is mostly going to depend on how tough the marking scheme is, I'd say I secured the B I needed though!


@inverting the Kc - why? If Kc > 1 then the forward reaction is favoured, if it is less than 1 the reverse reaction is favoured, so if you invert it you are actually getting Kc for the reverse of the equation, this wasn't specified in the question?

Hayezer

Burette filler I said to prevent contamination and ensure more accurate result?

And the sodium tartrate colour in rates of reaction I said green-pink-green, instead of pink-green-pink . I get any marks?

kyle84

id say u did

leaveiton

Dicksboro_man wrote: »

What did we all say why PH3 bonding is different to the rest of the molecules?

Completely guessed that one but I said it was non-polar covalent and the others were polar covalent due to the difference in electronegativity values

dmca93

Ah sure you wouldn't want to suck it up anyway, would you?:P Hope they don't dock if it isin't needed!!

For the PH3 I said it wasn't polar and the rest were, it was the only thing I could think of and I justified it with electronegativity values. I don't know if that is right though because they specifically asked about polar bonds at the end of the questions......

Mista

leaveiton wrote: »

Completely guessed that one but I said it was non-polar covalent and the others were polar covalent due to the difference in electronegativity values

Thats what I said

TheHazer

Dicksboro_man wrote: »

What did we all say why PH3 bonding is different to the rest of the molecules?

I said about them being non-polar due to the electronegativity difference being only .01 you?

Hayezer

Ok so for question 1 the calculations wer you meant to divide by two yes ?

Geo10

leaveiton wrote: »

Completely guessed that one but I said it was non-polar covalent and the others were polar covalent due to the difference in electronegativity values

I said that too!
For the last part of Q5 did anyone else say that the bcl3 molecules would be non polar due to symmetry?

TMCGY

Whats the substance that used to be added to petrol but now is stopped??

Nazata

Geo10 wrote: »

I said that too!
For the last part of Q5 did anyone else say that the bcl3 molecules would be non polar due to symmetry?

Yes, the centre of positive and negative charges lie at the same point due to its geometric shape so it's non polar

Geo10

TMCGY wrote: »

Whats the substance that used to be added to petrol but now is stopped??

I said lead?

dmca93

I said lead.