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CHEMISTRY PAPER 1 HERE

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aquarian93:
is a burette is used for a very accurate amount compared to a pipette?

aquarian93:
this is from may 05, if anyone has solved it, pls help me.
for question 16, the answer is D

y cnt it b C? pls help, thanks in advance

MR.BooMBastiC:
burette!!!!!!

i did in 1 of da  past pprs

esso:
pippete is to measure fixed volumes...like 25 cm3 or 30 cm3

but burrete is vry accurate ,when compared with m.cylinder,and its used to measure varying volumes,like 35.5 or 47.2

hope i helped...

nid404:

--- Quote from: esso on June 11, 2009, 02:34:49 pm ---An aqueous solution contains barium iodide.
It is possible to obtain a solution that contains Ba2+(aq) but no I–(aq) by adding ……1…… until no
more ……2…… precipitate forms.

Which words correctly complete gaps 1 and 2?
1                                             2
A aqueous lead(II) nitrate         white
B aqueous lead(II) nitrate         yellow
C dilute sulphuric acid               white
D dilute sulphuric acid               yellow


help please...need an explanation..


--- End quote ---
U omit C and D first cuz if u want barium ions in the solution that reacting it with acid gives sulphate which is not soluble.
Since u want barium ions to be in the solution, u want iodide to precipitate so that it can be filtered. So u add Lead nitrate and this will react with barium iodide to give barium nitrate and lead iodide(which is yellow). lead iodide can be filtered as it is insoluble and will precipitate. the solution will contain no iodide ions.

I hope it's clear... :-\

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