Calculations in Short Response (2 Viewers)

[snorelacks]

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]

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

 

[j808]

I think i got around 9.9g for Galvanic Cell

yeah im pretty sure i got that too

 

[muzeikchun852]

what was the question for galvanic cell ?

 

[Official]

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

 

[silence--]

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]

I think I got all the calculation incorrect tbh...

 

[CalumGemmell]

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]

Dont u have to divide the conc by 10 since it was diluted 10x?

 

[matthewhearne]

I forgot Citric acid was triproctic! NOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!!

 

[CalumGemmell]

Dont u have to divide the conc by 10 since it was diluted 10x?

Nope, you'd have to multiple by 10, seeing as it was ten times more concentrated before it was diluted by the factor of 10.

 

[Reikira]

Ah shit fml.. there goes some marks..

 

[jamesfirst]

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]

Was it copper 2 or 1? Cause i recalled it being just copper >.<

 

[HyperComplexxx]

Mass of Ni = 9 point something
Concentration of NickelNitrate was = 0.13 soemthing

Concentration of Citric = 0.3 something

 

[CombustionManX]

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]

got them all right!

except for 1

but still looking at state rank bby

 

[sonispucca]

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...

 

[khorne]

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.

 

[CombustionManX]

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.