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

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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)
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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.
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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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