AQA AS Chemistry 7404/1 and 7404/2 - 27th May 2016 and 10th June 2016

Reply 580

sameer99

7

guys have any of you done the set 2 specimen paper?

Reply 581

sameer99

7

Original post by haes

CGP

same, that book does have mistakes and does't explain some things that well

Reply 582

17lina

3

You know the definition for saturated means "contains single bonds only" according to a mark scheme, then is a carbon with a cation classifed as a saturated hydrocarbon or an unsaturated hydrocarbon?

Also the free radical substituion part, it says the CFCs were banned and scientists developed safer alternatives that didnot contain chlorine, doesthis mean fluorine cannot act as a free radical?? Cz im pretty sure i saw bromine as a free radical the other day

Thanks xx

Reply 583

17lina

3

Original post by monoman

For a larger conical flask, the concentration of the particles is less. Therefore, there are fewer collisons and the reaction is slower, which makes it takes longer for the reaction to be completed

Thats because the volume has increased, concentration will decrease following n=CV which means less collisions between molecules and slower rate of reaction x

Reply 584

AdamWallisjr

2

Original post by sameer99

guys have any of you done the set 2 specimen paper?

Nope, do you have a link?

Reply 585

sameer99

7

http://www.thestudentroom.co.uk/showthread.php?t=4074387&highlight=AQA+as+chemistry+specimen#primary_content

here you go :smile:

Reply 586

sameer99

7

and if i were you, i would go onto youtube and watch Dr Orchard's walkthrough for the paper

Reply 587

AdamWallisjr

2

Original post by sameer99

and if i were you, i would go onto youtube and watch Dr Orchard's walkthrough for the paper

Ok, thx

Reply 588

Lola1244

5

Original post by Jkelly-11

If you do nucleophilic substitution with CN to something like 3-bromopentane and have to name the compound formed, does the carbon bonded to the nitrogen become carbon number 1 and therefore have the name as 2-ethylbutanenitrile

yes it does become carbon one, and you are right about the name.

Reply 589

17lina

3

Original post by tajtsracc

Could someone sum up Required Practical 5: Distillation of a product from a reaction? The textbooks that I have don't sum it up all that well. :/

So its basically purifying the product in this case cyclohexene from cyclohexanol

1) Add concentrated H2SO4 and H3PO4 in the flask containing cyclohexanol
2)Add boiling chips as well to make it boil more calmly
3)Set up the distillation apparatus (thermometer, condenser, flask)
4) Heat the mixture up to 83C so that every chemicals with bo 83 will evaporate
5)The condenser contains water, which will turn gas to liquid and it will be collected to the flask

6)Pour the product into the separating funnel and add water
7)The aqueous layer should be drained off in the bottom and there will be impure cyclohexene left behind

8)Pour it into a flask
9)Add anhydrous CaCl2 and leave it for 20 min so that it will dry
10)Distilling the product and the gases that boil at 83C will be pure cyclohexene

Hope this helps
Basically the textbook but how I memorised it in 10 steps x

Reply 590

Jkelly-11

1

Original post by Lola1244

yes it does become carbon one, and you are right about the name.

Thanks!

Reply 591

Alicehopps

1

Well it's definitely not an unsaturated hydrocarbon because it doesn't contain any double bonds but then it isn't exactly saturated???? If I had to go with one I'd go with saturated but I don't think it's either tbh.

If you use fluorine instead the C-F bond is a lot stronger so it doesn't break up in the atmosphere hence no ozone depletion. However if you use bromine the C-Br bond is a lot weaker so it breaks before it reaches the upper atmosphere before the ozone layer hence no ozone depletion either.

Reply 592

username1292215

22

Do you guys think aby Pv=nRT stuff will come up

Reply 593

AdamWallisjr

2

Original post by 17lina

So its basically purifying the product in this case cyclohexene from cyclohexanol

1) Add concentrated H2SO4 and H3PO4 in the flask containing cyclohexanol
2)Add boiling chips as well to make it boil more calmly
3)Set up the distillation apparatus (thermometer, condenser, flask)
4) Heat the mixture up to 83C so that every chemicals with bo 83 will evaporate
5)The condenser contains water, which will turn gas to liquid and it will be collected to the flask

6)Pour the product into the separating funnel and add water
7)The aqueous layer should be drained off in the bottom and there will be impure cyclohexene left behind

8)Pour it into a flask
9)Add anhydrous CaCl2 and leave it for 20 min so that it will dry
10)Distilling the product and the gases that boil at 83C will be pure cyclohexene

Hope this helps
Basically the textbook but how I memorised it in 10 steps x

Do you need to have both H2SO4 and H3PO4 or just one of the two???

Reply 594

GabbytheGreek_48

11

Original post by Laam13

Do you think bonding questions will come up? Paper 1 was pretty full of them so what do you think?

Posted from TSR Mobile

personally i dont think you should rule it out as aqa can put anything on the test that the spec says and they might do bonding again to catch people out