Qualification > Sciences
IGCSE CHEMISTRY DOUBTS
Ivo:
--- Quote from: anonymous7 on June 03, 2010, 02:14:19 pm ---Okay, I have a question.
May/June 2004, Paper 3, Question 4, (b)(ii)
Why the difference between the height of the precipitate between Iron (II) and Iron (III) salts?
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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
Ivo:
--- Quote from: jellybeans on June 03, 2010, 02:38:09 pm ---i) how do you draw the structure of the polymer formed from but-2-ene?
--- End quote ---
Here we go!
jellybeans:
--- Quote from: Ivo on June 03, 2010, 02:51:46 pm ---Here we go!
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THANKS :D
--- Quote from: jellybeans on June 03, 2010, 02:38:09 pm ---ii) How do you deduce the formula of the alkene which has a relative molecular mass of 168?
is it something to do with the empirical formula of... idk CnH2n hence 3n = 168 ... blahblah
lol help please! THANKS.
--- End quote ---
:D
Ivo:
--- Quote from: jellybeans on June 03, 2010, 02:38:09 pm ---ii) How do you deduce the formula of the alkene which has a relative molecular mass of 168?
is it something to do with the empirical formula of... idk CnH2n hence 3n = 168 ... blahblah
lol help please! THANKS.
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We know C has Ar of 12 and H is 1. So by using CnH2n:
12n + 2n = 168
So n = 12
So C12H24
jellybeans:
--- Quote from: Ivo on June 03, 2010, 03:02:23 pm ---We know C has Ar of 12 and H is 1. So by using CnH2n:
12n + 2n = 168
So n = 12
So C12H24
--- End quote ---
THANKS ;D
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