Can someone pls explain how to do this Chemistry MC question (1 Viewer)

[TK123]

The question is from the 2021 CSSA multiple choice. Usually, these questions aren't very difficult, so I thought that I must not be seeing something in the question. For reference, the correct answer is C

 

[carrotsss]

least error filled cssa paper

one of my friends sent me this a while back im p sure the answer was incorrect

 

[TK123]

least error filled cssa paper

one of my friends sent me this a while back im p sure the answer was incorrect

Yeah ok lol, kinda thought so considering most of the short-answer solutions were so atrocious as well. Do u have any suggestions for other trial papers to do other than Grammar/Ruse/NSBHS?

 

[carrotsss]

Yeah ok lol, kinda thought so considering most of the short-answer solutions were so atrocious as well. Do u have any suggestions for other trial papers to do other than Grammar/Ruse/NSBHS?

those are like exactly the ones I’d recommend whoops, other than that the PEAK trials are pretty nice if you can get your hands on them, Sydney boys are pretty good and NEAP are fine asw as independent

 

[Interdice]

Was the answer D?

 

[Interdice]

Pb + 2HCl -> PbCl2 + H2

[HCl] = 0.0978
n(HCl) = 0.003594
n(pb2+) = 0.001797
[Pb] = 0.0712

Am I correct? I suck at chem

 

[carrotsss]

Pb + 2HCl -> PbCl2 + H2

[HCl] = 0.0978
n(HCl) = 0.003594
n(pb2+) = 0.001797
[Pb] = 0.0712

Am I correct? I suck at chem

yep cssa just sucks

 

[Unovan]

Pb + 2HCl -> PbCl2 + H2

[HCl] = 0.0978
n(HCl) = 0.003594
n(pb2+) = 0.001797
[Pb] = 0.0712

Am I correct? I suck at chem

what is that signature

 

[nsw..wollongong]

what is that signature

u just now noticed

 

[Interdice]

what is that signature

It's from the game of thornes. Where Drogo and Deanerys have sex

 

[Luukas.2]

View attachment 40949

The question is from the 2021 CSSA multiple choice. Usually, these questions aren't very difficult, so I thought that I must not be seeing something in the question. For reference, the correct answer is C

None of the answers given are correct.

Anything based on the precipitation of PbCl₂ being complete is wrong because the information given is that lead(II) chloride has just started to precipitate. Hence, it is a K_sp problem and not a titration calculation. You use the value of K_sp and the concentration of chloride ions present in the diluted mixture to determine the concentration of Pb²⁺ (which is one of the answers) but then need to calculate what it was in the original (undiluted) solution.

 

[TankKuno]

Yeah ok lol, kinda thought so considering most of the short-answer solutions were so atrocious as well. Do u have any suggestions for other trial papers to do other than Grammar/Ruse/NSBHS?

sbhs??

i can send to ppl if they want it, with marking criteria as well??

 

[synthesisFR]

sbhs??

i can send to ppl if they want it, with marking criteria as well??

send it i ran out of papers plss

 

[TankKuno]

send it i ran out of papers plss

hehe brb

 

[TankKuno]

ALSO IM GATEKEEPING THEM HEHEHE, NOT FOR PUBLIC VIEW, U WANT THEM U MSG ME
muahahhahaha

 

[carrotsss]

send it i ran out of papers plss

how I sent you 100

 

[synthesisFR]

how I sent you 100

ok when i mean all of them i mean like the worthwhile ones
the other ones r trash ngl

 

[Interdice]

None of the answers given are correct.

Anything based on the precipitation of PbCl₂ being complete is wrong because the information given is that lead(II) chloride has just started to precipitate. Hence, it is a K_sp problem and not a titration calculation. You use the value of K_sp and the concentration of chloride ions present in the diluted mixture to determine the concentration of Pb²⁺ (which is one of the answers) but then need to calculate what it was in the original (undiluted) solution.

I'm retarded. But moreso is CSSA

 

[Unovan]

I'm retarded. But moreso is CSSA

your calc working out was correct just a flawed question dont stress