Chemistry Paper 61

[Saadiya Ahmed]

I wrote yellow ppt will form

I hope bth our ans get marked right!! :|

 

[bluefa1con]

u cant check the crystals for impurity in chromatography
you will have to make a solution

to check any crystal for purity for check its melting point

 

[Saadiya Ahmed]

idk if I'm ryt, but I wrote da temp rise wud b less coz sum of da heat wud b absorbed by da copper.

Wont temp rise b greater if copper is a good conductor?!

 

[IGCSE O/L student]

Wont temp rise b greater if copper is a good conductor?!

oh, idk!

 

[ThatReallyReallyWeirdDude]

I hope bth our ans get marked right!! :|

Well
If you look at wikipedia Lead Chloride is a white solid
Silver Chloride is also a white solid (AFAIK)
I wrote that the limit will be reached at 3cm^3 instead of 6cm^3 because of the different mole ratio with different reactions

 

[IGCSE O/L student]

even i wrote the same :\

me 2!

 

[IGCSE O/L student]

Melting point. not boiling people.

Chromatography MAY be right.

it IS ryt, my teacher said so. cn u stop bein da BOSS plzz? u r actin lyk u knw evrythin n da rest of us knw nothin. evrybody makes mistakes. it's not lyk we r perfect!!!

 

[Saadiya Ahmed]

Well
If you look at wikipedia Lead Chloride is a white solid
Silver Chloride is also a white solid (AFAIK)
I wrote that the limit will be reached at 3cm^3 instead of 6cm^3 because of the different mole ratio with different reactions

Okayyy....now im confused...:/

 

[mania _ manal]

heyy guys isnt ironsulphate hydrated thus if we heat for a longer tym it will loose water

 

[EpicLol]

I hope bth our ans get marked right!! :|

which question is this for?

 

[natsume hyuga]

heyy guys isnt ironsulphate hydrated thus if we heat for a longer tym it will loose water

there wasnt water .. it was only a solution (not aqueous ) of iron sulphate...it will get oxidated or sumthing like that and turn red brown. Trust me i didnt write that but some girl who is superb told me that...

 

[ThatReallyReallyWeirdDude]

it IS ryt, my teacher said so. cn u stop bein da BOSS plzz? u r actin lyk u knw evrythin n da rest of us knw nothin. evrybody makes mistakes. it's not lyk we r perfect!!!

Hey
come on
He's only trying to help. He never said you guys are stupider than him or anything like that.
As far as I know chromatography IS right - dissolve it in distilled water, make chromatogram. Melting point may actually bring complications since when heating the water of crystallization will escape, but whatever.

Okayyy....now im confused...:/

THe original reaction is:
Pb(NO3)2 + 2KCl -> PbCl2 + 2KNO3
So for every one mole of Pb you need 2 moles of KCl
The new reaction with Silver Nitrate is
AgNO3 + KCl -> AgCl + KNO3
Now the mole ratio is onene
So now you need half the amount of moles (and thus volume) of KCl to react with the same amount of nitrate.

 

[EpicLol]

heyy guys isnt ironsulphate hydrated thus if we heat for a longer tym it will loose water

yes it does get dehydrated but since it said heating for a long time in the question, it will split up into iron 3 oxide, sulfur dioxide and sulfur trioxide.....i got this info from my teacher and online so I think its rite....

 

[IGCSE O/L student]

Hey
come on
He's only trying to help. He never said you guys are stupider than him or anything like that.
As far as I know chromatography IS right - dissolve it in distilled water, make chromatogram. Melting point may actually bring complications since when heating the water of crystallization will escape, but whatever.

THe original reaction is:
Pb(NO3)2 + 2KCl -> PbCl2 + 2KNO3
So for every one mole of Pb you need 2 moles of KCl
The new reaction with Silver Nitrate is
AgNO3 + KCl -> AgCl + KNO3
Now the mole ratio is onene
So now you need half the amount of moles (and thus volume) of KCl to react with the same amount of nitrate.

yeah, but still. he acts lyk dat. it's lyk he's makin fun of evry1 by findin faults in deir ans.

 

[ThatReallyReallyWeirdDude]

there wasnt water .. it was only a solution (not aqueous ) of iron sulphate...it will get oxidated or sumthing like that and turn red brown. Trust me i didnt write that but some girl who is superb told me that...

If it's a solution that means it's aqueous. Aqueous means dissolved in water to give a solution :|
Oxidated? That makes no sense.
When you heat it water will evaporate; that causes a) a saturated solution and furthermore b)crystallization

 

[EpicLol]

yeah, but still. he acts lyk dat. it's lyk he's makin fun of evry1 by findin faults in deir ans.

come on... if u think he behaves that way then just ignore him....dont lose yr temper.....I mean if I think someone is annyoing I just ignore them.....I think he is just trying to help though....

 

[ThatReallyReallyWeirdDude]

yeah, but still. he acts lyk dat. it's lyk he's makin fun of evry1 by findin faults in deir ans.

No
He just points out the correct (or whatever he thinks is correct)
It's how YOU look at it.
He may be brash but most of us look at it as "He's trying to help us."
The way you look at it just makes me think that you're jealous or something. "Hmph, he got it right, I got it wrong. He's acting like he's the boss."

 

[EpicLol]

I hope bth our ans get marked right!! :|

which question was this?

 

[thats_me]

Hey
come on
He's only trying to help. He never said you guys are stupider than him or anything like that.
As far as I know chromatography IS right - dissolve it in distilled water, make chromatogram. Melting point may actually bring complications since when heating the water of crystallization will escape, but whatever.

THe original reaction is:
Pb(NO3)2 + 2KCl -> PbCl2 + 2KNO3
So for every one mole of Pb you need 2 moles of KCl
The new reaction with Silver Nitrate is
AgNO3 + KCl -> AgCl + KNO3
Now the mole ratio is onene
So now you need half the amount of moles (and thus volume) of KCl to react with the same amount of nitrate.

couldnt the ans b sumthin related to bromide n silver being less reactive than the other 2 i guess i did a lot of blunders :S

 

[natsume hyuga]

u will get marks and I don't thnk that mass is included.......plz check the post I posted of the similar question which came before see it!

i know this is stupid but for that question i didnt mention expose to air and water at all. It completely slipped my mind, what bad luck. So straight away zero out of 7 right?