DomGunstone
Badges: 0
Rep:
?
#1
Report Thread starter 6 years ago
#1
General discussion on F331 resit exam coming up this Thursday.

I am feeling fairly confident about it. I guess my weakness is the calculations...
0
reply
aks786
Badges: 0
Rep:
?
#2
Report 6 years ago
#2
learn them then buddy
0
reply
DomGunstone
Badges: 0
Rep:
?
#3
Report Thread starter 6 years ago
#3
(Original post by aks786)
learn them then buddy
How many different calculations are there do you reckon, on the whole syllabus?
0
reply
aks786
Badges: 0
Rep:
?
#4
Report 6 years ago
#4
i have no idea
1
reply
GurlLikeRosie_x
Badges: 0
Rep:
?
#5
Report 6 years ago
#5
(Original post by DomGunstone)
How many different calculations are there do you reckon, on the whole syllabus?
Ummmm, a few!

MOLE CALCULATIONS
MASS CALCULATIONS
CALCULATIONS INVOLVING GASES
CONCENTRATION CALCULATIONS
0
reply
GurlLikeRosie_x
Badges: 0
Rep:
?
#6
Report 6 years ago
#6
How are you guys revising for chemistry on thursday, reading storylines & then reading the book + pastpapers!

do you have any techiques?
0
reply
LAZYABDI
Badges: 2
Rep:
?
#7
Report 6 years ago
#7
I suck at chemistry revision even though the concepts are piss easy but this book makes me fall a sleep every time. Started today covered all of Elements of Life with story line plus the book and hopefully 2 papers this afternoon. Should be ready for thursday i hope.
0
reply
amber109
Badges: 1
Rep:
?
#8
Report 6 years ago
#8
how did you guys do on this exam before, if this is your retake?
0
reply
Dude Ranch
Badges: 2
Rep:
?
#9
Report 6 years ago
#9
anyone know what roughly you need to get 90 UMS on this paper? I have 77 but Im trying to get full marks as I find the A2 a bit harder.
0
reply
ArifK
Badges: 0
Rep:
?
#10
Report 6 years ago
#10
How much harder does it get at A2?
0
reply
TheAsian
Badges: 9
Rep:
?
#11
Report 6 years ago
#11
I love the calculations, tbh!
My weaknesses are:
Hess' law
Enthalpy change (I don't know where to put the +/-???)
The frequency crap; the unique lines and gaps and stuff? Lol, any notes/ tips?
0
reply
Kreayshawn
Badges: 0
Rep:
?
#12
Report 6 years ago
#12
can anyone explain this question to me: June 12 3)d)
it's a calculation question I don't understand
0
reply
baddeleyh
Badges: 0
Rep:
?
#13
Report 6 years ago
#13
Do we need to know the solubility rules for F331?


Posted from TSR Mobile
0
reply
baddeleyh
Badges: 0
Rep:
?
#14
Report 6 years ago
#14
Do we need to know the solubility rules?


Posted from TSR Mobile
0
reply
ambbs
Badges: 12
Rep:
?
#15
Report 6 years ago
#15
I didn't take the exam in jan but for those who did - what would you recommend focussing on, and looking back at jan, do you have any tips? :-) Want to do well in this unit particularly because unit 2 seems a lot worse!


Posted from TSR Mobile
0
reply
ambbs
Badges: 12
Rep:
?
#16
Report 6 years ago
#16
(Original post by baddeleyh)
Do we need to know the solubility rules?


Posted from TSR Mobile
What do you mean? Rules for what? :-)


Posted from TSR Mobile
0
reply
AMELIA-x
Badges: 0
Rep:
?
#17
Report 6 years ago
#17
Any predictions for what is going to come up? 😊


Posted from TSR Mobile
0
reply
DomGunstone
Badges: 0
Rep:
?
#18
Report Thread starter 6 years ago
#18
(Original post by baddeleyh)
Do we need to know the solubility rules?
I think they were pretty simple.

I saw a question that gave the solubility of a compound to 100g of water

It asked for the solubility in moles of the compound per 100g

The answer was just:

MOLES = Solubility / Mr
0
reply
DomGunstone
Badges: 0
Rep:
?
#19
Report Thread starter 6 years ago
#19
(Original post by Kreayshawn)
can anyone explain this question to me: June 12 3)d)
it's a calculation question I don't understand
Yes, it's pretty easy once you get your head around it:

The question is asking for the volume of air required for combustion of 60cm3

We know that the ration of isooctane to oxygen is 1 to 12.5 (1:12.5)

So we need to multiply the amount of moles of oxygen by the volume of isooctane (both are 60 times larger, still follow ratio)

12.5 * 60 = 750 (Volume of oxygen in the air mixture)

Because we know that air is 21% oxygen, we can say that in 100 molecules, 21 of them are oxygen. Therefore the amount of moles of oxygen to isooctane:

100 / 21 = 4.7619047619

Ratio =
1 : 4.7619047619

So, there must be this times many more isooctane than oxygen:

750 * 4.7619047619 = 3571.42857143

The question requires this is dm3 therefore we need to divide by 1000

3571.42857143 / 1000 = 3.57dm3

I'm sorry for the late reply. I hope this helped.
1
reply
Kreayshawn
Badges: 0
Rep:
?
#20
Report 6 years ago
#20
(Original post by DomGunstone)
Yes, it's pretty easy once you get your head around it:

The question is asking for the volume of air required for combustion of 60cm3

We know that the ration of isooctane to oxygen is 1 to 12.5 (1:12.5)

So we need to multiply the amount of moles of oxygen by the volume of isooctane (both are 60 times larger, still follow ratio)

12.5 * 60 = 750 (Volume of oxygen in the air mixture)

Because we know that air is 21% oxygen, we can say that in 100 molecules, 21 of them are oxygen. Therefore the amount of moles of oxygen to isooctane:

100 / 21 = 4.7619047619

Ratio =
1 : 4.7619047619

So, there must be this times many more isooctane than oxygen:

750 * 4.7619047619 = 3571.42857143

The question requires this is dm3 therefore we need to divide by 1000

3571.42857143 / 1000 = 3.57dm3

I'm sorry for the late reply. I hope this helped.
thanks - I get it now

Another question I had is when you are drawing a dot and cross diagram with a double bond, do we draw them as

x
o
x
o

OR as

xo
ox

does that make sense?
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of Hull
    Undergraduate Open Day Undergraduate
    Sat, 23 Nov '19
  • Edge Hill University
    All Faculties - Undergraduate and Postgraduate Undergraduate
    Sat, 23 Nov '19
  • Keele University
    Undergraduate Open Day Undergraduate
    Sat, 23 Nov '19

What offers have you received from universities?

Unconditional (53)
21.03%
Unconditional if firmed (20)
7.94%
Unconditional if insurance (2)
0.79%
Both unconditional and unconditional if firm/insurance (6)
2.38%
No unconditional offers (171)
67.86%

Watched Threads

View All