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Author Topic: Chemistry Help HERE ONLY !!  (Read 106114 times)

Offline crypsAnity

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Re: Chemistry Help HERE ONLY !!
« Reply #645 on: May 31, 2009, 03:21:45 pm »
@ Clem.. your friend was right .. it is because it has one OH group .. and amino acids are different .. they do not have only an OH group..
they have COOH .. which is the functional group for carboxylic acids.. but thats not the case anywyas they polymerise because they have two different functional groups placed end to end on their molecule ..  so u have to visualize .. u see.. they form a polymer each and evrytime
by adding on to the different group endings .. sorta like laterally inverting evrytime ..

so basically ..yeah ethane, 1,2 diol can polymerise because it has two functional group at both the endings.. whereas butan-1-ol .. just has one.. so it cant link up continuously..
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Offline IGSTUDENT

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Re: Chemistry Help HERE ONLY !!
« Reply #646 on: May 31, 2009, 03:23:37 pm »
CAN SOMEONE HELP..

I NEED SYMBOL EQUATION FOR REACTION BETWEEN ETHANOIC ACID AND SODIUM HYDROXIDE?
NOVEMBER 2005 ...IS IT A REVERSIBLE REACTION?
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Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #647 on: May 31, 2009, 03:30:17 pm »
it would have same effect of normal acid. so it would be a netralisation reaction giving sodium ethanoate and water

ch3cooh + NaOH ---> Ch3COONa + H2O

and no its not reversible..
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Offline Shogun

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Re: Chemistry Help HERE ONLY !!
« Reply #648 on: May 31, 2009, 03:34:15 pm »
ok, i have a question, see:
1) how can i show in caculation tht a substance is in excess?
2)why to make alloys with metal is better than making with non metals?
3)y do sientist believe tht no undiscovered eliment is missing from the periodic table?

and By the way Thanks emi..
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one who masters both the pen and paper is indeed a true warrior.

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Offline sweetie

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Re: Chemistry Help HERE ONLY !!
« Reply #649 on: May 31, 2009, 03:35:32 pm »
fear_fear da formula u used is rong da rite one is < mass/relative molecular mass>
and in <cl2>  der is only one mole of chlorine

hope i helped
All the best
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Offline ~M.J~

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Re: Chemistry Help HERE ONLY !!
« Reply #650 on: May 31, 2009, 04:01:23 pm »
Quote from: thukon on May 31, 2009, 05:54:13 am
A classmate told me a good mnemonic for the reactivity series, but it goes by the first letter of the element
Please- Potassium
Send- Sodium
Lord- Lithium
Charles- Calcium
McClain- Magnesium
A- Aluminium
Zebra- Zinc
If- Iron
The- Tin
Lame- Lead
Horse- Hydrogen
Cannot- Copper
Munch- Mercury
Sweet- Silver
Grass- Gold
No point in adding one for platinum, because it goes at the end anyway. Where does carbon go in this?

@aquarian. In exothermic, more heat is given out than taken in by the reaction. In endothermic, more heat is taken in than given out.
addition of carbon and Platinum and its like this
Please- Potassium
Send- Sodium
Lord- Lithium
Charles- Calcium
McClain- Magnesium
A- Aluminium
Cute- Carbon
Zebra- Zinc
If- Iron
The- Tin
Lame- Lead
Horse- Hydrogen
Cannot- Copper
Munch- Mercury
Sweet- Silver
Grass- Gold
Properly- Platinum
« Last Edit: May 31, 2009, 04:03:26 pm by ~M.J~ »
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nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #651 on: May 31, 2009, 04:08:13 pm »
Quote from: Shogun on May 31, 2009, 03:34:15 pm
ok, i have a question, see:
1) how can i show in caculation tht a substance is in excess?
2)why to make alloys with metal is better than making with non metals?
3)y do sientist believe tht no undiscovered eliment is missing from the periodic table?

and By the way Thanks emi..

1) check mole ratio(if u give me a question i might be able to explain)
2)metallic bonding is in layers, forces are non-directional, which makes them malleable. Non-metals do no have layers and are brittle.
3)the elements in a periodic table are arranged according to their increasing atomic numbers. Atomic number increases consecutively with the current elements, there is therefore no missing element in the table.

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Offline aquarian93

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Re: Chemistry Help HERE ONLY !!
« Reply #652 on: May 31, 2009, 04:09:42 pm »
i need help wid question 3 c the 2nd part.
chem p3 oct 2008

anyone care to help? i dont get it.


thanks
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Offline Ghost Of Highbury

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Re: Chemistry Help HERE ONLY !!
« Reply #653 on: May 31, 2009, 04:12:20 pm »
which variant??
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Offline Priceless

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Re: Chemistry Help HERE ONLY !!
« Reply #654 on: May 31, 2009, 04:15:00 pm »
ya shogun....

4 da 1st ques...as nid404 said check mole ratio...da 1 dat has a higher mole no is in excess.
4 ur 2nd n 3rd wues nid404 is completely right..

gud luck 2 evry1  ;)
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Offline Ghost Of Highbury

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Re: Chemistry Help HERE ONLY !!
« Reply #655 on: May 31, 2009, 04:15:31 pm »
okk..got it so it will be (56*2)/196 *100 = 57.1 %
 :)
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Offline Priceless

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Re: Chemistry Help HERE ONLY !!
« Reply #656 on: May 31, 2009, 04:16:45 pm »
Quote from: aquarian93 on May 31, 2009, 04:09:42 pm
i need help wid question 3 c the 2nd part.
chem p3 oct 2008

anyone care to help? i dont get it.


thanks

lol i wz just gonna say da same thng1!!! gud luck 2 u both ;)
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Don't say "God I have tooo many problems" but say "Problems I have God!"   Gud Luck 2 all 4 xams. Hope v all du well.....fingers crossed LOL

nid404

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Re: Chemistry Help HERE ONLY !!
« Reply #657 on: May 31, 2009, 04:20:44 pm »
Quote from: aquarian93 on May 31, 2009, 04:09:42 pm
i need help wid question 3 c the 2nd part.
chem p3 oct 2008

anyone care to help? i dont get it.


thanks

1st variant

Mass of 1 mol of the hydrated oxide=196g
Mass of iron=56x2=112g
%iron in the oxide=112/196x100=57%

2nd variant

mass of water=36g
%water in the oxide=36/196x100=18.4%
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Offline Ghost Of Highbury

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Re: Chemistry Help HERE ONLY !!
« Reply #658 on: May 31, 2009, 04:21:55 pm »
hahaha nid,,
answered both of themm

was abt to do that..
lol.. :)
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Offline aquarian93

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Re: Chemistry Help HERE ONLY !!
« Reply #659 on: May 31, 2009, 04:28:48 pm »
thanks guys!
i was toking abt 1st variant
bt guys, i dnt get how u get 57%

the mass is 196
hw do u get 112? :S

and in the same paper i dont understand 5b the third part, cn sum1 explain pls? thank you!
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