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Physics, Chemistry and Biology: Post your doubts here!

imperial

imperial

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great, thanks, but how you got the number of moles of cobalt chloride and the one below it (the one with .h2o)
 
Maz

Maz

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imperial said:
great, thanks, but how you got the number of moles of cobalt chloride and the one below it (the one with .h2o)
Click to expand...
The mole ratio between HCl and CoCl2 is 2HCl:1CoCl2
Therefore, 0.08:0.04.
The same method is applied in the next one too.
 
AAnsarii

AAnsarii

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kainat husain said:
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s04_qp_3.pdf
4b (ii) how the grid will b cux b4 they usediron (III) chloride now they'll use iron (II) chloride? how will i make out the difference?
(iii) also
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c if ur using iron (III) Cl [FeCl3], more OH will b used, coz it'll make Fe(OH)3, n when u use iron(II)Cl [FeCl2], lesser OH will b used, Fe(OH)2, so d graph's max will b at 8 coz when OH was 3, it was 12, so when it is 2, it will b 12/3 *2 = 8

ur centrifuging n all dat..so u'll c ppt. in AlOH3, remember d qualitative analysis, d ppt dissolves in xcess NaOH? that'll apply here.
c d ms, v hlpful

sorry, m bad xplainr, all d best
 
E

EpicLol

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AAnsarii said:
c if ur using iron (III) Cl [FeCl3], more OH will b used, coz it'll make Fe(OH)3, n when u use iron(II)Cl [FeCl2], lesser OH will b used, Fe(OH)2, so d graph's max will b at 8 coz when OH was 3, it was 12, so when it is 2, it will b 12/3 *2 = 8

ur centrifuging n all dat..so u'll c ppt. in AlOH3, remember d qualitative analysis, d ppt dissolves in xcess NaOH? that'll apply here.
c d ms, v hlpful

sorry, m bad xplainr, all d best
Click to expand...

Yr not a bad explainer!
 
thats_me

thats_me

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IGSCE.Geek. said:
ahhhhhhhhhhhh help me im mj 2007 question 7d plz!!
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Alright..
Iodine number basically is a test for unsaturated hydrocarbon ,to check the number of double bonds present in it
So here you have fat , 1 mole of fat is 884 and 100gof fat react with 86.2g of iodine
the question is 884 react with how many grams of iodine? so u cross multiply i.e if 100 is 86.2 then 884 is how much?
(100*884)/86.2=762
Now that u have the mass(762g) of iodine , the next question is how many moles is it?
No. of moles= mass/Molar mass , mass =762 & Molar mass is =127 (from periodic table)
=762/127*2=3
U found the no of mole of I2 that react with 1 mole of fat i.e 3 (1 mole of I2 reacts with one double bond (frm question))
So number of doule bonds fat has is 3
 
imperial

imperial

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i need help in esters in general
so here some questions:
draw me a simple ester (dont use same carbon number in alcohol and acid, like ethyl ethanoate, or propyl propanoate)
what is hydrolysis of esters?
any other reactions?

need a HELP ASAP IN ESTERS PLEASE
 
M

Manobilly

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Terelyne is an ester ,it is formed by reaction between ethane 1 ,2 diol and benzene di carboxylic acid.
 
imperial

imperial

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Manobilly said:
Terelyne is an ester ,it is formed by reaction between ethane 1 ,2 diol and benzene di carboxylic acid.
Click to expand...

wait isnt terylene is a polyester of the ester monomer which is formed between ethane 1,2 diol and benzene di carboxylic acid?
 
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