the perfect titre......!!!!!

[boy2011]

ya my paper was 33 and ur teacher confirmed us dat it was 28....

 

[boy2011]

sorry our teacher confirmed not ur.

 

[junaidaftab]

This can not be right. Hassam said that it was 29.4 and as I said, no one got a titre below 29.00 in our center. :|

 

[boy2011]

well titrate value differs lab to lab they will chek according to the value of our examiner and my examiner was my teacher so he also gt 28

 

[Anonymousx3]

Well, my practical was absolutely awful.
I might have JUST got a C or something. :/
Is there any chance I can still get an overall A?

 

[sniper7137]

@Anonymousx3: Yes you can still get an A with a C in practical.

And i don't think the titre has to be the same for each lab. The teachers for that school perform the practical and the values of the candidates should be close to the values of the teachers. 8)

 

[bionology]

the lab supervisor does the titration himself and sends his ans too to the CIE, it can vary, we and our supervisor got 28cm3

 

[MAVtKnmJ]

Unnecessary posts deleted, please stay on topic.

 

[mrpaudel]

doesnot matter....depends on the supervisor who also does the practical and send the report to CIE...mine was 26.5 ...n m sure its correct...!!

 

[junaidaftab]

You're right, guys, but look at this way. The salt we got was Mohr's salt and 1 mol of Mohrs salt contains 14% Fe (calculated it from Wikipedia). Now, whatever the concentration of Mohr's salt maybe, it'd always contain 14% Fe and the correct titre to obtain 14% as the answer is 29.8 cm^3 given the conc. of KMn04. What can I say? I don't know how supervisors work. :|

 

[boy2011]

btw wat was the improvement in that q2?

 

[junaidaftab]

I wrote that insulate the crucible with a cotton lagging and try to heat the crucible at constant temperature which, of course, would be different for strong and gentle heating. Is the first one correct?

 

[junaidaftab]

Btw, I am still confused about that titration thingy. :|

 

[pradeep]

hey! i got messed up with the given mass of chemical to conduct the titration. so measured mass was a bit low. thus this soln with low conc. changed the titre value to 24. But the % which was to be calculated at last is the same one. Does this affect much with the marking?

 

[hassam]

u shud hav said using balnce reading to a greater precision......or cooling in a dessicator to ensure it didnt absorb moisture while cooling......

 

[ra_shan158]

i got 29.05cm3
and what about ions in both fa6 n fa7...plzz every1 do reply

 

[olenka1611]

Well our titre's were different from each other... mine was 28.8 and i am sure its correct... the salts F5 was a carbonate salt F6 Was Ammonium Chloride and F7 was Sulfuric acid... if i am not wrong) and what abt that percentage question last question? what was the method everyone used?

 

[intel1993]

Fa6 was amoonium bromide nt chloride..............

 

[msk]

29.8 cm*3......those who got this are in dreamland,,,,others in HELL.....this calculation will lead to exact percentage of fe2+ in mohr salt

u can,t say it was 29.8 because we had to make a solution and that depends upon the mass u take so i got 31! my examiner got 30.85...as per marking scheme within 0.2 of examiner u get all the accuracy marks!

 

[olenka1611]

Yeah! Sure ! mistyped!) Can anyone help... on how to drwa constructuin lines on the graph to find no. of moles? just like in paper may june 2007 2 (e)??