Chemistry P33 Anions/Cations

[Babuzar]

wrote Mg instead of Mn! But rest were same

 

[ds29]

quick summary for everyone.

This is for Paper 33
Your Enthalpy of Solution can vary - It depends on the conditions that you were given, like the temperature of the cold water, the room temperature (therefore the amount of heat absorbed by the surroundings), and so many other factors. So even people who got errors from 1% to 25% shouldn't worry, it all depends on what values that your teacher calculated and sent to cambridges in their appropriate practical sheet.
If you got a value close to 15.2 +- 10 then consider that you did good for that question.

For the 2nd one though it's more fixed.
Anions: Sulphate, Carbonate, Sulphate & Carbonate - The last one had both anions
Cations: Cu2+, NH4+, Cobalt (although we didn't have to mention it), Mn2+

If you got the anions and cations correct then you'll get full marks for that part as well

 

[eddiegal]

i got only sulpahte for the first nd sulphate nd carbonate both for the odr two=S

 

[mista.lova.lova]

i got only sulpahte for the first nd sulphate nd carbonate both for the odr two=S

FOR P33 chemistry:
man....i also got sulphate in all FA2-3-4, and carbonate in FA 3 n 4....
i also confirmed from my frnds aftr practical, n they also agreed wid me....

i added bacl2 to all three, white ppt formed, then i added baNO3 to all new fresh soln, they also gave white ppt....

then hw come chloride be one of the anions???? :S:S:S

 

[eddiegal]

lol chloride isnt there...if u r referring to the very first post then yes theres a posibilty tht the solutions fa5,6,7 nd 8 had chloride in them but since we were testng those for their cations it doesnt matter lol but sum1 plzzz confirm the sulphate carbonate part

 

[mista.lova.lova]

i had answers same as many of the students doing my same practical..

yea,,, bt smone elso also plz confirm.. :O

 

[ds29]

This is how the practical for sulphate carbonate test is done.
First you a aqueous barium ions. Maybe BaCl2
You will get a white precipitate for all 3 solutions.
However for a sulphate the white precipitate won't dissolve in excess acid.
So you need to add excess acid to the white ppt.
Only the 2nd one dissolves to give a colourless solutions.

 

[shahroze2]

can any one please confirm the anion tests for chemistry paper 33

 

[duffer geek]

hey dere was no cobalt!!!!!!!!!!!!!!!!!!!! which prac paper dd u guyz giv???????????????? :shock:
but dere were Mg, NH4, and Cu for sure!!
my percentage difference was way too big though like > 60 :?:
time managment was hell lot difficult but thanks god i completed ma paper :? wen u've 2 heat water using spirit lamp. sm students were given some ex time wen they protested!!!!!!! :x
dont tel me i m stupid 4 askin it but the reaction was endothermic, right?????????
n as for testing anions u had 2 add HCL 1st cuz it would react with any CO3 present and produce CO2 so that only So4 ould be left to form ppt with Ba. Otherwise ppt would form in all 3............ i dd it so i know it 4 sure!!!!!!!! :roll:

 

[duffer geek]

nooooooooooooooooooooooooooooooooooooooooooooooooooo
dis cnt b rtite !!!!!!!!!!!!!
my results showed the presence of CO3 in FA4 and FA3 while SO4 in FA2 and FA3

 

[eddiegal]

lol its a rule tht uwhenever u test for sulphates u always add Ba2+ first nd then the acid..i read it sumwhere but forgot the reasoning=p

 

[hamizahmed]

willa anyone xplain me w=hat had to be done in the calculation part in which specific heat capacity of the beaker had to be added???? I believe it was not supposed to be added directly, first the capacity had to to be multiplied ny temp and than had to be added with energy.

 

[Hasnain.Jaffer]

willa anyone xplain me w=hat had to be done in the calculation part in which specific heat capacity of the beaker had to be added???? I believe it was not supposed to be added directly, first the capacity had to to be multiplied ny temp and than had to be added with energy.

yep i did the same !!

 

[hamizahmed]

although I did not do it this way...

 

[hamizahmed]

but what was the correct method?????

 

[sami]

I have added the HCL FIRST, to test for the carbonate, by observing the effervecence...then i added BACL2 to test for sulfate , which should form a white ppt. It wasnt a test to deffirentiate between sulfate and sulfite,where you had to add BaCl2 and the HcL to test for the solubility of the white ppt, Will get full marks for get the correct observations and right conclusions???

 

[mahad]

WELL people the reason why you should have added the barium salt first and then the acid was that if the ppt were soluble then it was a sulphite which OBVIOUSLY isn't a sulphate and for that we had to write that sulphate was absent. So if you didn't add the acid later you would have seen a white ppt in all of the 3 reagents and you would have wrote that sulphates were present in all three which wasn't the case.

 

[sami]

What do you zohaib think??? :!: and mahad, there werent any sulfites........!!

 

[sami]

no reply???

 

[Glowing light]

the only thing i did right in this practical was my Question 2..=P