Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 334805 times)

Offline The Golden Girl =D

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2130 on: May 24, 2010, 10:25:36 pm »
explain plz i m sry i m realli dumb

ethanol..................draw them and u'll kno what i'm talkin abt

By the way no one is dumb  ;)
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2131 on: May 24, 2010, 10:25:52 pm »
can u plz explain y this thank u any1
 :)

there is no equation as such .. Fe2O3.xH2O because the water content is not the same in all cases

Rusting requires
CO2
H2O
O2

Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2132 on: May 24, 2010, 10:27:03 pm »
there is no equation as such .. Fe2O3.xH2O because the water content is not the same in all cases

Rusting requires
CO2
H2O
O2

c02? why would u need that?
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2133 on: May 24, 2010, 10:27:29 pm »
Can someone explain Q4, 22 of w08 paper, thanks

For Q4, recall that IONIC COMPOUNDS are SOLUBLE in water while COVALENT COMPOUNDS are NOT.
In the first method, X, i.e the ionic salt, will dissolve in the water, as is soluble, leaving Y behind.
Y, as a solid residue, may be obtained via filtering, where X is in solution.

In method 2, Usually both DO NOT dissolve in ethanol.

So only method one is workable, thus the answer is B.


In Q22,
experiment 1 is a simple test for the presence of ammonium ion. recall that sodium hydroxide is added to an ammonium containing compound. Alkaline ammonia gas will produce on heating, turning the red paper blue, and the other blue will remain blue.
In experiment 2, a soluble salt CANNOT react with an acid, so no reaction, thus no change in colour of litmus paper.
Thus ans is D.
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2134 on: May 24, 2010, 10:27:45 pm »
explain plz i m sry i m realli dumb

C, because has formula: C2H5OH
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2135 on: May 24, 2010, 10:28:18 pm »
explain plz i m sry i m realli dumb
   
     H   H  
     |    |        
H - C - C - O - H
      |   |      
      H   H  

ETHANOL C2H5OH
« Last Edit: June 05, 2010, 05:49:27 am by ~VIN1094~ »

Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2136 on: May 24, 2010, 10:29:07 pm »
Yo noobs go to sleep we are failing anyways xD  ;D ;D

Lol m gonna stay for another half an hour :P Anyone wants to ask :)?
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Offline The Golden Girl =D

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2137 on: May 24, 2010, 10:30:40 pm »
Yo noobs go to sleep we are failing anyways xD  ;D ;D

Lol m gonna stay for another half an hour :P Anyone wants to ask :)?

nah actually i'm going to bed

Talk to you later people of this universe  ::)
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2138 on: May 24, 2010, 10:33:26 pm »
For Q4, recall that IONIC COMPOUNDS are SOLUBLE in water while COVALENT COMPOUNDS are NOT.
In the first method, X, i.e the ionic salt, will dissolve in the water, as is soluble, leaving Y behind.
Y, as a solid residue, may be obtained via filtering, where X is in solution.

In method 2, Usually both DO NOT dissolve in ethanol.

So only method one is workable, thus the answer is B.


In Q22,
experiment 1 is a simple test for the presence of ammonium ion. recall that sodium hydroxide is added to an ammonium containing compound. Alkaline ammonia gas will produce on heating, turning the red paper blue, and the other blue will remain blue.
In experiment 2, a soluble salt CANNOT react with an acid, so no reaction, thus no change in colour of litmus paper.
Thus ans is D.

Ok, I get 22.  BUt for 4, why in MS it says A?  So apparantly ionic salts are not soluble in ethanol butr organic covalent are?   
Always willing to help!  8)
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Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2139 on: May 24, 2010, 10:34:11 pm »
Ok, I get 22.  BUt for 4, why in MS it says A?  So apparantly ionic salts are not soluble in ethanol butr organic covalent are?   

yes
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Offline NidZ- Hero

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2140 on: May 24, 2010, 10:34:17 pm »
ethanol..................draw them and u'll kno what i'm talkin abt

By the way no one is dumb  ;)
but dat dumb ms is sayin its ethene i noe i m nt dumb :P was makin sure of de answer

Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2141 on: May 24, 2010, 10:37:29 pm »
Ok, I get 22.  BUt for 4, why in MS it says A?  So apparantly ionic salts are not soluble in ethanol butr organic covalent are?   

So, apparently, COVALENT ORGANIC COMPOUNDS are SOLUBLE in ETHANOL! :S
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2142 on: May 24, 2010, 10:41:09 pm »
So, apparently, COVALENT ORGANIC COMPOUNDS are SOLUBLE in ETHANOL! :S

Can anyone explain why ionic are insoluble and organic covalent are soluble in ethanol?
Always willing to help!  8)
"In helping others, we shall help ourselves, for whatever good we give out completes the circle and comes back to us."

Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2143 on: May 24, 2010, 10:44:00 pm »
Can anyone explain why ionic are insoluble and organic covalent are soluble in ethanol?

Somestuff my son, can't be explained -.- >.< Seriously, why do u want to confuse ur self? I don't think anyone here knows why cuz its so detailed... U dont need to know ;)
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Offline the_grim_reaper

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2144 on: May 24, 2010, 10:46:14 pm »
Can anyone explain why ionic are insoluble and organic covalent are soluble in ethanol?

Yar Shaz guide parh guide!!!!

@ VIN why is CO2 needed for rusting???? Heard it for the first time in my  life ....