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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 354241 times)

Offline haris94

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #780 on: May 15, 2010, 11:53:21 pm »
i hv a query:
what solvents can u use in chromatography and does the solvent u use depend on what u r extracting?

eg. in this question from O/N 2009 chem p6

7) Leaves from trees contain a mixture of coloured pigments which are not soluble in water. A
student was given these two instructions to investigate the pigments in the leaves.
1. Crush some leaves to extract the coloured pigments.
2. Use the liquid extract to find the number of coloured pigments in the leaves.
(a) What would the student need in order to effectively carry out instruction 1?

the ms says pestle/mortar/solvent/sand (any three)
ignore water and/or heat

why  ??? ???

Thanks

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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #781 on: May 16, 2010, 12:13:39 am »
yes the solvent always deends on what u are extracing.. and in this case its not water ! cz it tells you in the question that its isnoluble in water..so what you say is..use suitable solvent which dissolves the pigments..and explaint hte chromatofrphy process..



it says ignore water and heat cz its insoluble in water..altho i think heating with the SUITABLE SOLVENT should work..but anyway if u write that you dont get marked down i guess..so pestle adn morart is enough for crushing.

i hhave no idea what teh sand is for ? probably like filtering water...you put pigments in solvent and put it in sand and the insoluble stuff wont penetrate?
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Offline WARRIOR

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #782 on: May 16, 2010, 01:27:21 am »
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NO secrets to SUCCESS , it is the result of 1.HARD WORK 2.GOOD PREPARATION 3.LEARNING FROM FAILURE
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nid404

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #783 on: May 16, 2010, 05:10:24 am »
for b when ammonium chloride is warmed, it gives out ammonia and HCl

NH4Cl----> NH3 + HCl

do you get it now...?

NH3 turns red litmus blue(basic)
HCl turns blue litmus red (acidic)
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #784 on: May 16, 2010, 05:59:02 am »
how can boiling something wid water <eg: jam> extract the colour?????
confusing
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #785 on: May 16, 2010, 06:06:38 am »
how will u noe hw many dots 2 make in chromatography?????
bcoz in m/j q2 d) 2006 i made 2 bt in ms its 3 y??? n hw????
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nid404

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #786 on: May 16, 2010, 06:08:05 am »
Quote from: 6394 on May 16, 2010, 06:06:38 am
how will u noe hw many dots 2 make in chromatography?????
bcoz in m/j q2 d) 2006 i made 2 bt in ms its 3 y??? n hw????

1 dot at the origin + n dots (where n is the no of different substances in the chemical mixture)
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #787 on: May 16, 2010, 06:16:42 am »
Quote from: nid404 on May 16, 2010, 06:08:05 am
1 dot at the origin + n dots (where n is the no of different substances in the chemical mixture)
but they didnt tel in this ppr
????
here is the ques:
A sample of orange fruit jam was investigated to check the three colourings present.
Step 1 The jam was boiled with water.
Step 2 The mixture was filtered.
Step 3 The filtrate was concentrated.
Step 4 The concentrate was analysed by chromatography.
(a) What was the purpose of Step 1?
[1]
(b) Why was the mixture filtered?
[1]
(c) How was Step 3 carried out?
[1]
(d) Draw a diagram to show the possible paper chromatogram obtained in Step 4.
jus answer part d dat hw did u noe dat 3 dots r presnt
THANX
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Offline High-R

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #788 on: May 16, 2010, 06:17:48 am »
@nid404
but see how do u know 3 dots..specifically...because in tht paper..its just said tht its a jam...and we r doing chromatagrophy of its mixture..after these steps:
2 A sample of orange fruit jam was investigated to check the three colourings present.
Step 1 The jam was boiled with water.
Step 2 The mixture was filtered.
Step 3 The filtrate was concentrated.
Step 4 The concentrate was analysed by chromatography.
then after Q1 a,b,c,......
..its d they ask: Draw a diagram to show the possible paper chromatogram obtained in Step 4.

so can u tell us if they just meant to make it maximum 3 (like not less than 3)...or its only ryt for specifically three dots
....and is the line dot or spot counted as 1??
Thanks....do reply
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Offline High-R

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #789 on: May 16, 2010, 06:21:15 am »
OMG i got it...sorry..thts so dumbo of me!!..got it!!
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #790 on: May 16, 2010, 06:21:58 am »
Quote from: hamz on May 16, 2010, 06:17:48 am
@nid404
but see how do u know 3 dots..specifically...because in tht paper..its just said tht its a jam...and we r doing chromatagrophy of its mixture..after these steps:
2 A sample of orange fruit jam was investigated to check the three colourings present.
Step 1 The jam was boiled with water.
Step 2 The mixture was filtered.
Step 3 The filtrate was concentrated.
Step 4 The concentrate was analysed by chromatography.
then after Q1 a,b,c,......
..its d they ask: Draw a diagram to show the possible paper chromatogram obtained in Step 4.

so can u tell us if they just meant to make it maximum 3 (like not less than 3)...or its only ryt for specifically three dots
....and is the line dot or spot counted as 1??
Thanks....do reply
*slap on head*
Thanks a loot
rofl
:P
=D
ya i saw it
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #791 on: May 16, 2010, 06:23:04 am »
Quote from: hamz on May 16, 2010, 06:21:15 am
OMG i got it...sorry..thts so dumbo of me!!..got it!!
sree tok the rong quote
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #792 on: May 16, 2010, 06:24:17 am »
Quote from: hamz on May 16, 2010, 06:21:15 am
OMG i got it...sorry..thts so dumbo of me!!..got it!!
oh hey hamza
rofl same doubt haan
copy cater
jk=P
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Offline High-R

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #793 on: May 16, 2010, 06:28:43 am »
hi...6394....lol not copycater!!!
we r doin the paper together!!!...u see!!!
so oviously watever we didnt undertsand!!...we both ask on the forum..lol
..hehe.....Thanks nid404 anywz!!!
 ;D
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6394

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #794 on: May 16, 2010, 06:31:35 am »
Quote from: hamz on May 16, 2010, 06:28:43 am
hi...6394....lol not copycater!!!
we r doin the paper together!!!...u see!!!
so oviously watever we didnt undertsand!!...we both ask on the forum..lol
..hehe.....Thanks nid404 anywz!!!
 ;D
ok lts stop wasting tym tel me hw did u do dat graph ??????
increasing iis from the readings we hve got bt wat abt dec.
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