Calculations in Short Response (1 Viewer)

snorelacks

Member
Joined
Aug 6, 2011
Messages
53
Gender
Female
HSC
2011
Anyone can share their answers for the calculations in Section II? (Galvanic cell and titrations)

Seriously I thought this exam was much harder, and I basically screwed up calculations :(
 

Reikira

Member
Joined
Mar 8, 2010
Messages
68
Gender
Male
HSC
2012
I think i got around 9.9g for Galvanic Cell

and 0.03 or 0.003 for the titration one.

idunno i fink i screwed it up
 

Official

Bring it on
Joined
Feb 18, 2009
Messages
962
Location
Over the Moon
Gender
Male
HSC
2011
answers for calc:

around 9.9g ish for the galvanic cell
0.13M ish for the concentration in the same q
0.35M ish citric acid dilute or not dilute im not sure
 
Last edited:

silence--

Member
Joined
Apr 16, 2009
Messages
246
Gender
Male
HSC
2011
yeah i got around 9.9g or sth for galvanic

around 0.31 for citric acid concentration (or maybe 3.1? but that seems a bit high, i dont remember really except my answer had 3's and 1's in it)

dont remember my answer for the second part of galvanic (concentration of nickel), think i may have made a silly there anyway :/
 

jamesfirst

Active Member
Joined
Jan 30, 2010
Messages
2,020
Gender
Male
HSC
2011
I think I got all the calculation incorrect tbh...
 

CalumGemmell

Member
Joined
Aug 29, 2011
Messages
45
Gender
Male
HSC
2011
I got 7 point something for the mass of the nickel, and I can't remember the conc one. For citric acid I got 0.33
 

Reikira

Member
Joined
Mar 8, 2010
Messages
68
Gender
Male
HSC
2012
Dont u have to divide the conc by 10 since it was diluted 10x?
 

matthewhearne

Member
Joined
Mar 17, 2010
Messages
33
Gender
Male
HSC
2011
I forgot Citric acid was triproctic! NOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!!
 

jamesfirst

Active Member
Joined
Jan 30, 2010
Messages
2,020
Gender
Male
HSC
2011
I could not understand the titration question at all so I just did some random sht


and got 7.xxx x 10^-3 M ... LOL
 

Kamishiro

New Member
Joined
Nov 11, 2009
Messages
6
Gender
Male
HSC
2011
Was it copper 2 or 1? Cause i recalled it being just copper >.<
 

HyperComplexxx

ლ(ಠ_ಠ ლ)
Joined
Jan 12, 2011
Messages
460
Location
behind you
Gender
Undisclosed
HSC
2011
Mass of Ni = 9 point something
Concentration of NickelNitrate was = 0.13 soemthing

Concentration of Citric = 0.3 something
 
Joined
Jan 26, 2010
Messages
70
Gender
Male
HSC
2011
Uni Grad
2015
answers for calc:

around 9.9g ish for the galvanic cell
0.13M ish for the concentration in the same q
0.35M ish citric acid dilute or not dilute im not sure
Weren't you supposed to calculate the citric acid concentration in the original undiluted cordial sample (or whatever it was)? I got 0.31M for the diluted and then since it was diluted by a factor of 10 (making 50mL to 500mL then taking a 25mL sample or whatever) I multiplied it by 10 to get the original concentration of 3.1M. It seemed a little high but I figured there's a reason why cordial generally has to be diluted a lot before you can drink it.
 

crazybea

Member
Joined
Nov 2, 2011
Messages
94
Gender
Undisclosed
HSC
N/A
got them all right!

except for 1

but still looking at state rank bby
 

sonispucca

New Member
Joined
Nov 10, 2009
Messages
28
Gender
Female
HSC
2011
In short:
It however was diluted from an initial 50 to 500ml prior to titration, thus degree of concentration was 1/10 when titrated, hence true concentration was 0.031/1/10 = 0.031 x 10/1 = 0.31mol/L or so.
OH SHIT! I can't believe i forgot to x by 10, i always do that. What is this i dont even...
 
K

khorne

Guest
Was it copper 2 or 1? Cause i recalled it being just copper >.<
You could use either, as either would be valid. Cu(I)NO3 is on the table of redox and Cu(II)(No3)2 is also valid. You will get different masses depending on which one you chose, as balancing is required.
 
Joined
Jan 26, 2010
Messages
70
Gender
Male
HSC
2011
Uni Grad
2015
FUCK! Just checked it, for 3.1M of citric acid you would need over 500g of it to be dissolved. Damn it. I guess thats one mark gone for a calculation error somewhere.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top