[EAP]

What did people put for the overall dipole thing? I put that it did have an overall dipole because it is a tetrahedral shape and so the individual dipoles don't cancel out ?

[Zhy]

(Original post by laura111294)
Is there an unofficial mark scheme anywhere?

This was posted from The Student Room's Android App on my HTC Desire

Yes, it is called this thread.

[dongonaeatu]

(Original post by EAP)
What did people put for the overall dipole thing? I put that it did have an overall dipole because it is a tetrahedral shape and so the individual dipoles don't cancel out ?

i said it didn't have an overall dipole as it was symmetrical so the charges cancel out

[Mattywooda]

(Original post by EAP)
What did people put for the overall dipole thing? I put that it did have an overall dipole because it is a tetrahedral shape and so the individual dipoles don't cancel out ?

Uhh it is a dipole but not cause of the shape. It would cancel if it were CCl4, but it wasnt =o so it is a dipole because charge isnt symmetrical as F is so electronegative.

[EAP]

(Original post by dongonaeatu)
i said it didn't have an overall dipole as it was symmetrical so the charges cancel out

But I swear tetrahedrals aren't symmetrical?

[dongonaeatu]

(Original post by EAP)
But I swear tetrahedrals aren't symmetrical?

ah well, got that wrong then lol.

[gstarwill]

[QUOTE=Mattywooda;37721040]I wrote it out =)


yea i saw that after i wrote it! got the same as you. I rounded 0.02608 or whatever to .0261.. 3 sig fig? or was the answer they wanted .02608..

[Mattywooda]

(Original post by gstarwill)

(Original post by Mattywooda)
I wrote it out =)

yea i saw that after i wrote it! got the same as you. I rounded 0.02608 or whatever to .0261.. 3 sig fig? or was the answer they wanted .02608..

There was a mark for 3sf =)

[gstarwill]

I am so annoyed i left the overall charge question as "No".. i finished about 50 minutes early, and i was literally just contemplating whether or not tto change it to "yes" and speak about flourine's electronegativity.. i ended up leaving it as no but writing fluorine is more electronegative.. MAYBE one mark.. probably not though haha!

[EAP]

(Original post by Mattywooda)
Uhh it is a dipole but not cause of the shape. It would cancel if it were CCl4, but it wasnt =o so it is a dipole because charge isnt symmetrical as F is so electronegative.

Oh, oops! I put that it was because it didn't have symmetry and so the dipoles don't cancel. I just looked it up on the Internet and it said this : CCl3F does have a permanent dipole; ∑ΔEN ≠ 0 and the molecule is not symmetrical

Do you reckon I could have got one mark?

[dongonaeatu]

[QUOTE=gstarwill;37721169]

(Original post by Mattywooda)
I wrote it out =)


yea i saw that after i wrote it! got the same as you. I rounded 0.02608 or whatever to .0261.. 3 sig fig? or was the answer they wanted .02608..

it is 0.0261 as 3 sf does not count the first 0's. so essentially the important numbers are 260 which are 3sf and the 8 next to these is above 5 so it because 0.00261

[Beffnaay]

(Original post by Mattywooda)
Uhh it is a dipole but not cause of the shape. It would cancel if it were CCl4, but it wasnt =o so it is a dipole because charge isnt symmetrical as F is so electronegative.

I put that it is polar because all the delta negative chlorines were in the same direction and they wouldn't cancel out as the Fluorine didn't have any lone pairs. Just one fluorine won't mean there isn't a dipole i'm sure? It's not much more electronegative than chlorine?

[Mattywooda]

(Original post by EAP)
Oh, oops! I put that it was because it didn't have symmetry and so the dipoles don't cancel. I just looked it up on the Internet and it said this : CCl3F does have a permanent dipole; ∑ΔEN ≠ 0 and the molecule is not symmetrical

Do you reckon I could have got one mark?

Yeah, of course - it was two marks one for yes/no, one for why =)

EDIT:

(Original post by Beffnaay)
I put that it is polar because all the delta negative chlorines were in the same direction and they wouldn't cancel out as the Fluorine didn't have any lone pairs. Just one fluorine won't mean there isn't a dipole i'm sure? It's not much more electronegative than chlorine?

Yeah, but not all the Cl is counteracting the fluorine charge - it's not linear. Google CFCl3 and see what the internet says (Y)

[Lily Academia]

(Original post by suncake)
Just looked at the bleach bottle in my bathroom and it's not flammable, just irritant. The glimmer of hope remains!

(Original post by suncake)
You also shouldn't clean with something that might explode in your face and destroy your beautiful kitchen worktops/bathroom fixtures.

Well... that's what I'm telling myself. Team Flammable.

My answer was just...ohdear. Read it back just as invigilator took it in; bit dramatic:

"It's flammable. This is undesirable.
And dangerous."

Mhmm, No kidding

[gstarwill]

(Original post by Mattywooda)
There was a mark for 3sf =)

yea i know.. so 0.02608 would get full marks?

I wrote 0.0261. is this full marks? (also showed my working)

[Mattywooda]

(Original post by gstarwill)
yea i know.. so 0.02608 would get full marks?

I wrote 0.0261. is this full marks? (also showed my working)

0.02608 would get 2

0.0261 would get 3 =)

[dongonaeatu]

(Original post by Lily Academia)
My answer was just...ohdear. Read it back just as invigilator took it in; bit dramatic:

"It's flammable. This is undesirable.
And dangerous."

Mhmm, No kidding

well you would still get the mark.

[Harantony]

Darn! I didn't:
- Write sulphur dioxide and only 'sulphur'
- Say that that molecule was a tetrahedral shape
- Some other one which I can't remember

Silly mistakes: grr D:

[suncake]

(Original post by Lily Academia)
My answer was just...ohdear. Read it back just as invigilator took it in; bit dramatic:

"It's flammable. This is undesirable.
And dangerous."

Mhmm, No kidding

I don't know why but that made me laugh! Full stops to create tension and add extra emphasis?


Edit: why neg? D: I'm not saying it's wrong, cause that's what I put.. I'm just amused by the way she wrote it! *sigh*

[emhop]

(Original post by dongonaeatu)
well you would still get the mark.

Still maintaining you can't clean with a gas xD It's boiling point was too low to be a liquid...