Q17 (1 Viewer)

[k4t5UM0t0]

I hated that flame test question: i wrote it wasn't suitable because it is used to identify cations, sodium carbonate will be distinguishable as is barium nitrate though lead nitrate and HCl would be unidentifiable, hence wouldn't be suitable as the only method used.

 

[codyjh]

1)sodium carbonate
2)HCL
3)lead nitrate (i think)
4)barium nitrate (i think)

not sure if i put 3 and 4 in the right spot :s . least ill get 1 /2 lol

 

[codyjh]

I hated that flame test question: i wrote it wasn't suitable because it is used to identify cations, sodium carbonate will be distinguishable as is barium nitrate though lead nitrate and HCl would be unidentifiable, hence wouldn't be suitable as the only method used.

yeah i said something like that. not all the solutions would of given a colour ie: hcl and barium nitrate. people were sayin shit like if would of been toxic with the lead nitrate being vaporised. either way

 

[dwatt]

yeah i said something like that. not all the solutions would of given a colour ie: hcl and barium nitrate. people were sayin shit like if would of been toxic with the lead nitrate being vaporised. either way

Barium has a green flame colour. Because the other two cations also had flame tests, it should have been possible to deduce that the last was HCl (which has no flame colour like you say).

So I was pissed off with that question. You COULD flame test it. The reason it is unsuitable is because lead vapour is fairly toxic, which it is not on the syllabus for the list of flame colours we are supposed to be testing.

Still...could have done it in a fume cupboard.

 

[xclusv2bhung]

aww damn :

i did
HCl
sodium carbonate
lead nitrate
and other nitrate.

aww damnit .. but i kinda guessed the last two.

 

[aja152]

damn..... i got the whole thing wrong.................................grr

 

[codyjh]

Barium has a green flame colour. Because the other two cations also had flame tests, it should have been possible to deduce that the last was HCl (which has no flame colour like you say).

So I was pissed off with that question. You COULD flame test it. The reason it is unsuitable is because lead vapour is fairly toxic, which it is not on the syllabus for the list of flame colours we are supposed to be testing.

Still...could have done it in a fume cupboard.

yeah my bad

but how were we sposed to no the Pb2+ cations had a distinctive colour when i cant find it in and text book :s . only has precipitate tests. or were spose to assume that all metal ions produce a distinctive colour? BOS may take both answers ? :S confused lol

spose its only 1 mark... right?

 

[codyjh]

Barium has a green flame colour. Because the other two cations also had flame tests, it should have been possible to deduce that the last was HCl (which has no flame colour like you say).

So I was pissed off with that question. You COULD flame test it. The reason it is unsuitable is because lead vapour is fairly toxic, which it is not on the syllabus for the list of flame colours we are supposed to be testing.

Still...could have done it in a fume cupboard.

yeah my bad

but how were we sposed to no the Pb2+ cations had a distinctive colour when i cant find it in and text book :s . only has precipitate tests. or were spose to assume that all metal ions produce a distinctive colour? BOS may take both answers ? :S confused lol

spose its only 1 mark... right?

 

[conman]

All the carbonates will be precipitated so we can Na2C03 to be the one which cause 2 precipitation reactions and the rest are easy. HCl will react with Pb2+ to precipitate so leaving out BaC03 alone.

 

[mzduxx2006]

please help me solve it;
you had:
HCl
sodium carbonate
barium nitrate
lead nitrate

this is what i did in the exam but i got confused:
1+2= gas released (HCl and sodium carbonate, first thought)

2+4= no reaction
now from my first thought, 2 is either the acid or the carbonate...
barium nitrate + HCl gives no reaction so its possible
and now (1=sodium carbonate, 2= acid, 4=barium, only thing left is 3, = lead)

but...
3+4 = white precipitate? lead nitrate and barium nitrate definitely do not react...

this is probably all wrong now... any1 confident with their answer?

1 i had HCL

2 i had sodium

3 i had lead

4 i had barium

Pft probly not right but HEYY NO CHEMISTRYYYYYY EVERRRRR AGAIN

 

[mzduxx2006]

aww damn :

i did
HCl
sodium carbonate
lead nitrate
and other nitrate.

aww damnit .. but i kinda guessed the last two.

omg same order. ahah HI 5

 

[mzduxx2006]

I hated that flame test question: i wrote it wasn't suitable because it is used to identify cations, sodium carbonate will be distinguishable as is barium nitrate though lead nitrate and HCl would be unidentifiable, hence wouldn't be suitable as the only method used.

um i said someshit like flame tests are only suitable for identifying cations not anions. is that right?