Chemistry Unit 2 Edexcel, Exam- 23rd May 2012

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Reply 1180

xtron

Original post by lordmackery

What did people put for steam as a greenhouse gas?

Steam is a greenhouse gas because it absorbs IR radiation to make its bonds vibrate.

(edited 11 years ago)

Reply 1181

EffKayy

For the mixing with petrol one
Is 'smoother combustion' and 'to make it easily ignitable' on the same lines?

Also -->
Advantage of the reaction above to rather burning it directly.
I said steam is a renewable source :s-smilie:

Yeah or re-emits it

Original post by delphinas

Who can upload this paper please????

And was it 2-methyl-2-chloropropane or 2-chloro-2-mthylpropane ?????

:frown:

((

Either is acceptable

Reply 1184

Chaofan88

Original post by Arusa01

White ppt
brown gas produced? :smile:

I put the brown gas too :smile:

I guess white ppt is the metal oxide formed? I put yellow-orange flame too, I think. ****, looking back I may have misread it as calcium nitrate and put brick-red flame....ohhh maannnn

Reply 1185

EffKayy

Section A:

Spoiler

Section B:

Spoiler

Section C:

Spoiler

Cost of high pressure
Cost of strong pipes/reaction vessels needed to withstand high pressure (2)
Why is it better for reaction like this rather than combustion of methane directly ? (1)
Ammonia has a higher boiling point than methane: (4)
Ammonia has hydrogen bonding between molecules, Strongest intermolecular force,
More energy required to break hydrogen bonds, also has permanent dipole- dipole interactions.
Methane only has weak London forces
Ammonia also has more electrons, so more/stronger London forces

Two additional pieces of information required to compare fuels?
Atom economy..?
Availability..?
% Yield,
Products produced - if seperation is required, etc

‘pungent’ smell advantage (1)

Can be easily detected/identified if its there, also if there’s any leak you can identify it..? (1)
Why was petrol mixed with ammonia ? (1)
Makes combustion more smoother/easily ignitable

Hydrogen/Ammonia – not long term replacement as a fossil fuel (1)
Ammonia used as Hydrogen is made from the fossil fuels so would not be a good replacement. Biproduct of ammonia burning is not CO2

Grade boundary for an A ? 61/62

(edited 11 years ago)

Reply 1186

Arusa01

Original post by Chaofan88

I put the brown gas too :smile:

I guess white ppt is the metal oxide formed? I put yellow-orange flame too, I think. ****, looking back I may have misread it as calcium nitrate and put brick-red flame....ohhh maannnn

LOL, it was calcium nitrate and brick red flame would be right. :smile:

Reply 1187

itsmehello

For the multiple choice which one isn't a disproportionation reaction I put C which has HNO3 and yeah...

Reply 1188

EffKayy

Original post by itsmehello

For the multiple choice which one isn't a disproportionation reaction I put C which has HNO3 and yeah...

I put D..mm mm

Reply 1189

Blob2491

For the greenhouse gas question I put; absorbs IR due to dipole moment and re-radiates it back to earth. I didn't mention causing temperatures to rise, so would that be 1 or 2 marks?

Reply 1190

Dovah13

Original post by ice_man

i put '+hexane=pink'.

What did you guys put for the question where alcohol was added to a halogenoalkane, was the product an alkene?

do you mean purple?

Reply 1191

AS01

Original post by EffKayy

Section A:

Spoiler

Section B:

Spoiler

Section C:

Spoiler

Grade boundary for an A ? 61/62

Oxidation number of S is -2
NH₃+O₂--> N₂+ H₂O not balanced.
I wrote combustion of methane produce soot and some unburnt hydrocarbon.
for the one which things that need to be considered for fuels
-how easily can it ignite
-Yield of reaction?
-products of reaction

Reply 1192

itsmehello

Original post by EffKayy

I put D..mm mm

Oh noo

Reply 1193

EffKayy

Original post by Blob2491

For the greenhouse gas question I put; absorbs IR due to dipole moment and re-radiates it back to earth. I didn't mention causing temperatures to rise, so would that be 1 or 2 marks?

2 I think.
1 for absorbing IR etc
then re-radiating it back towards earth for another

Reply 1194

AS01

Original post by EffKayy

I put D..mm mm

I kept D as well coz it had Cu in only one of the product there were not other products containing Cu.

Reply 1195

EffKayy

Original post by AS01

What was the compound that they wanted oxidation number for?
Also did they want you to balance it.,.?

Reply 1196

Blob2491

Can't remember if I balanced anything lol...what's done is done
According to this I got around 65-62 =]

Reply 1197

salvequamtu

Ah damn for Ammonia's smell...
the advantage i wrote was that people would not drink it or wouldn't consider it either???
Would I get a mark :frown:

I know it sounds stupid :frown:

But I heard they put something in gasoline so that people don't drink it.

Reply 1198

AS01

Original post by EffKayy

What was the compound that they wanted oxidation number for?
Also did they want you to balance it.,.?

i think it was S₂F₂
and balancing you have to alwaz balance the reaction they never say you to balance it bt you have to.

Reply 1199

Dovah13

Original post by EffKayy

Section A:

Spoiler

Section B:

Spoiler

Section C:

Spoiler

Grade boundary for an A ? 61/62

if i draw the displayed formula for Butan-2-ol, Butan-1-ol and 2methyl propan-1-ol do i get any marks or do i lose them because i didn't write it like CH3CH2 CH(OH)CH3 etc.?