Qualification > Sciences
IGCSE CHEMISTRY DOUBTS
Ivo:
--- Quote from: 8T on June 04, 2010, 06:05:05 pm ---UMM.. Honestly no it didnt u answered b 1 when i asked for b2 and 3 but i still dnt get b2 and could u have a look at b3 ..
Thanks :)
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That was b)ii). Graph would level off at 8cm3. Explained in the previous post.
--- Quote from: Ivo on June 03, 2010, 02:40:53 pm ---OK, We know from the graph that 12cm3 of aqueous sodium hydroxide was needed to react with 4cm3 of aqueous iron(III) chloride. Because they were all at 1.0 mol/dm3, we therefore realise that 1 mole of aqueous iron (III) chloride reacted with 3 moles of aqueous sodium hydroxide. Therefore, the formula for the precipitate is Fe(OH)3.
For iron (II) chloride, we know the formula of the precipitate to be Fe(OH)2, and so for the same volume of aqueous iron (II) chloride - 4cm3, we know 8cm3 of sodium hydroxide was required. Therefore, you would need to draw the maximum height of the precipitate when volume has reached 8cm3.
Hope this has helped! ;D
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Ivo:
--- Quote from: 8T on June 04, 2010, 06:09:26 pm ---Hi again ..
In may june 08 varient 32 4 a 2 i think ms author has accidently balanced the equation by adding 2 before the H2O
Am i Right?
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Indeed. the variant 1 mark scheme is right though (doesn't have the 2 in front of it).
8T:
Could someone rexplain please may june 04 q4 b 2 ( i didnt get Ivo's explanation) and b 3 ??
8T:
--- Quote from: Ivo on June 04, 2010, 06:21:28 pm ---Indeed. the variant 1 mark scheme is right though (doesn't have the 2 in front of it).
--- End quote ---
Thanks.
8T:
May june 08 q 8 b 3 the first one my answer was N-H & C=O bonds is it correct & if not what is ?
the second one i dnt quite get what the ms says ??
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